Absorbent article with multi-layer folded absorbent core

ABSTRACT

Absorbent laminates and multi-layer, folded absorbent cores comprising the absorbent laminates for use in absorbent articles are presented. Specifically, multi-layer, folded absorbent cores are presented that are formed from an absorbent laminate comprising an absorbent layer between two tissue layers, in which the absorbent core includes a central channel running longitudinally along the core and crenellations profiled along the thickness of the core and providing enhanced liquid distribution across the core surface area or profile and improved liquid absorption into the laminate.

I. CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.14/634,718, filed on Feb. 27, 2015, which claims priority to U.S.Provisional Patent Application Ser. No. 61/946,595, filed on Feb. 28,2014, and to U.S. Provisional Patent Application Ser. No. 61/948,744,filed on Mar. 6, 2014, each of which are hereby incorporated byreference in their entirety.

II. FIELD OF THE INVENTION

The present invention relates generally to absorbent garments and,particularly, absorbent garments having multi-layer folded thinabsorbent cores.

III. BACKGROUND

Absorbent articles, such as baby diapers, training pants, adultincontinence products and other such absorbent products include atopsheet that is closest to the wearer, an outer, moisture-impermeablebacksheet, and an absorbent core. Over time the absorbent cores havebecome increasingly thinner with superabsorbent materials being includedin ever-increasing amounts in place of traditional cellulosic pulp andother fillers and absorbents. While these thinner,superabsorbent-containing cores provide advantages, such as, generallyoffering a better fit to the wearer, they also present variouschallenges. One such challenge relates to the acquisition anddistribution of liquid insults. In conventional core designs the liquidspreads radially from the point where it strikes, or insults, the core.Thus, rather than being dispersed across the core surface generally, itstransport is localized. This challenge is exacerbated by the issue ofgel blocking. Gel blocking refers to the blocking of liquid transportthrough the core by the swelling and gelling of the superabsorbentmaterial as it absorbs and retains liquid and swells. Gel blocking oftenleads to leakage from the absorbent article since the core does not havethe ability to absorb and retain liquid at the rate desired.

Prior designs have attempted, to varying degrees of success and in avariety of ways, to address these issues. These efforts have involvedthe selection of superabsorbent materials based on the materials'properties, the addition of acquisition and distribution layers on topof the cores, and the positioning of the superabsorbent materials in thecore in a variety of designs and arrangements.

The preferred embodiments discussed below seek to address some of thesedisadvantages in the prior art.

IV. SUMMARY OF THE INVENTION

The present invention relates generally to absorbent garments and,particularly, to thin, multi-layer folded absorbent cores for disposableabsorbent garments having improved absorbent properties, including rapidliquid acquisition, good core utilization and high SAP efficiency Themulti-layer folded absorbent core according to the present inventioncomprises an absorbent laminate that is folded in such a manner as topresent a central channel and multiple liquid pathways for greatlyenhanced distribution and acquisition of liquid within the core.

In accordance with one aspect of the present invention, there isprovided an absorbent core comprising an upper laminate layer, a lowerlaminate layer and an absorbent layer positioned between the upperlaminate layer and the lower laminate layer, the absorbent layercomprising greater than about 90 percent by weight super absorbentpolymer (SAP).

In certain aspects, the absorbent core further comprises a thirdlaminate layer between the upper laminate layer and the lower laminatelayer. In some embodiments, the third layer is disposed between theupper laminate layer and the absorbent layer. In still otherembodiments, the third laminate layer is disposed between the absorbentlayer and the lower laminate layer.

In specific embodiments, the longitudinally folded absorbent laminatecomprises a channel, which in certain other embodiments, is generallycentrally located relative to a longitudinal centerline. In otherembodiments, the channel extends along the length of the foldedlaminate. In yet other embodiments, the channel includes a channelinsert. In certain aspects, the channel insert is a material selectedfrom group consisting of tow fibers, nonwoven, and yarn. In still otheraspects, the channel insert comprises a material selected from groupconsisting of tow fibers, nonwoven, and yarn.

The longitudinally folded absorbent laminate preferably comprises atleast two laminate layers on each side of the channel. In certainembodiments, the two laminate layers on each side of the channelessentially form two ‘V’ structures, with the bottom side of each ‘V’structure joined to form the bottom of the channel and the top side ofthe ‘V’ structures are not joined, and form the top of the open channel.In still other aspects, the longitudinally folded absorbent laminateincludes at least two laminate layers on each side of the channel, andwhen unfolded and generally flat, the laminate is at least about 180%the width of the folded absorbent laminate.

In certain aspects, at least one of the upper laminate layer and thelower laminate layer of the folded absorbent laminate comprises atissue. In certain aspects, at least one of the upper laminate layer andthe lower laminate layer of the folded absorbent laminate comprisestissue selected from the group of tissues consisting of porous tissue,creped tissue, and standard tissue. In still other embodiments, at leastone of the upper laminate layer or the lower laminate layer of thefolded absorbent laminate comprises a synthetic nonwoven.

In certain aspects, the upper and lower laminate layers of the foldedabsorbent laminate are bonded to each other through non-adhesivebonding. In yet other aspects, the folded absorbent laminate furthercomprises an adhesive between the upper and lower laminate layers. Inspecific embodiments, the adhesive is applied between the upper laminatelayer and the lower laminate layer. In certain aspects, the adhesiveextends along at least one longitudinal edge of the laminate such thatthe upper laminate layer is adhered to the lower laminate layer.

In some aspects, the adhesive basis weight is less than about 10% of theSAP basis weight. In yet other embodiments, the adhesive is selectedfrom a group consisting of styrene-butadiene-styrene block copolymer(SBS) or styrene-isoprene-styrene (SIS).

In specific embodiments, the absorbent laminate of the absorbent core isfolded to form a longitudinally folded multi-layer absorbent laminate ofat least three layers and, in other embodiments laminates having four,five, six, seven, eight or nine layers. In still other aspects, themulti-layer absorbent laminate is part of a dual core. The dual core maycomprise a base core and a surge core, wherein the base core and/or thesurge core includes a longitudinally folded, multi-layer absorbentlaminate as described in the present application. In yet other aspects,the surge core and/or base core can include a longitudinally folded,multi-layer absorbent laminate further comprises a channel. In specificembodiments, the channel is generally centrally located relative to thelaminate width. In still other specific embodiments, the channel widthis from about 2 mm to about 50 mm wide.

In specific embodiments, the multi-layer absorbent laminate is part of adual core comprising a base core and a surge core. In certainembodiments, both the base core and the surge core comprise alongitudinally folded, multi-layer absorbent laminate. In specificembodiments, the surge core is nested within the channel of the basecore. In yet other embodiments, the surge core is nested within thechannel of the base core such that two additional channels are formedbetween the edges of the surge and the base core, thereby forming threetotal channels.

In certain aspects, the SAP in the absorbent core has centrifugeretention capacity (CRC) in the range of about 33-38 g/g. In certainaspects, the SAP in the absorbent core has a 0.7 SAP AAP, as measured inthe 6-layer laminate test, of at least about 20 g/g.

In yet still other embodiments, the SAP has a mean particle size in therange of about 250 μm to about 350 μm. In specific embodiments, lessthan 10% of the weight of the SAP particles reside in particles that aregreater than 500 μm. In certain aspects, the SAP is non-uniformlydistributed. In specific embodiments, a SAP with an absorption timebetween about 160 to about 220 seconds is used. In specific embodiments,the resultant asymmetry of the absorbent laminate is between about 1 andabout 2. In still other embodiments, SAP with an absorption time lessthan about 160 seconds is used and the resultant asymmetry is greaterthan about 4.

In specific embodiments, the SAP content of each layer of themulti-layer folded absorbent laminate is from about 40 gsm to about 150gsm. In still other embodiments, the total SAP content of themulti-layers of the folded laminate is from about 7.4 g. to about 18 g.In still other embodiments the total SAP content of the multi-layers ofthe folded laminate is between about 240 gsm to about 600 gsm.

In certain aspects, the core comprising the longitudinally folded,multi-layer absorbent laminate has a thickness of less than about 5 mmand, in other aspects, 4 mm, 3 mm or 2 mm.

In specific aspects, the core has side leakage that is less than about 5g.

In certain embodiments, the absorbent layer comprises a single layer ofSAP.

In still other embodiments, the absorbent laminate exhibits a 2 ml FreeSurface Absorption Time of less than about 10 seconds.

In accordance with other aspects of the present invention, there isprovided a disposable absorbent article comprising a body-facingtopsheet, a backsheet and an absorbent core comprising any of thelongitudinally folded, multi-layer absorbent laminates of the presentapplication.

In certain aspects, the disposable absorbent article further comprises athrough-air bonded (TAB) acquisition distribution layer (ADL) positionedbetween the topsheet and the absorbent core. In specific aspects, theADL width is a least 80% of folded core width.

In still other aspects, a layer of cellulosic acquisition fiber ispositioned between the topsheet of the absorbent article and theabsorbent core. In embodiments in which the cellulosic acquisition fiberlayer is included and contains SAP, the amount of SAP is no more than10% by weight SAP.

In certain aspects, the disposable absorbent article and the core arestable after an insult. In certain aspects, the core and the absorbentarticle have a stability rating of at least 35 drops.

In accordance with another aspect of the present invention, there isprovided an absorbent core comprising a longitudinally foldedmulti-layer absorbent laminate, the absorbent laminate comprising anupper laminate layer, a lower laminate layer, and an absorbent layerpositioned between the upper laminate layer and the lower laminatelayer, the absorbent layer containing SAP, wherein the absorbentlaminate is folded to form a longitudinally folded multi-layer absorbentlaminate of at least three layers. In some aspects, the SAP content ofeach layer of the multi-layer folded absorbent laminate is from about 40gsm to about 150 gsm. In other aspects, the total SAP content of themulti-layers of the folded laminate is from about 7.4 g. to about 18 g.In still other aspects, the total SAP content of the multi-layers of thefolded laminate is between about 240 gsm to about 600 gsm. In otheraspects still, the 0.7 psi AAP of the folded laminate is greater thanthe 0.7 psi AAP of the same total basis weight of SAP.

In some embodiments, the absorbent core further comprises a channelextending longitudinally along the folded absorbent laminate, a firstset of laminate layers positioned on one side of the channel and asecond set of laminate layers positioned on the other side of thechannel. In certain embodiments, the absorbent core comprises aplurality of liquid passageways positioned between the laminate layers.

In certain embodiments of the absorbent core, the folded absorbentlaminate has an interior interfacial area for liquid absorption that isgreater than one and one half times the surface area of the top surfaceof the folded laminate. In other embodiments of the absorbent core,certain of the liquid passageways open toward the central channel andcertain other of the liquid passageways open toward the sides of thefolded laminate.

In still other embodiments of the absorbent core, at least one liquidpassageway is positioned between the laminate layers and is open to thechannel that is at least 2 millimeters wide. In other aspects, thechannel is no greater than about 50 millimeters wide. In other aspectsstill, the absorbent core comprises a folded laminate that, whenunfolded and generally flat, is at least about 150% the width of thefolded absorbent laminate when folded.

In specific aspects of the absorbent core, at least one liquidpassageway of the longitudinally folded absorbent laminate is positionedbetween the laminate layers and open to the channel such that liquidflows away from the channel passing radially from the channel into thelaminate layers. In other embodiments, the absorbent core comprises atleast four laminate layers on each side of the channel. In specificembodiments, the absorbent core comprises a folded laminate that, whenunfolded and generally flat, is at least about 345% the width of thefolded absorbent laminate.

In certain aspects, the folded core comprises an absorbent layercomprising SAP. In certain aspects, the folded core comprises anabsorbent layer comprising, in addition to SAP, an adhesive positionedbetween the upper laminate layer and lower laminate layer holding theupper and lower laminate layers together. In still other embodiments,the adhesive comprises or is mixed with the SAP.

In still other embodiments, the longitudinally folded absorbent laminateof an absorbent core comprises at least six laminate layers. In certainembodiments, the longitudinally folded absorbent laminate of anabsorbent core comprises at least six laminate layers on each side of achannel. In specific embodiments, when the folded laminate, whenunfolded and generally flat, is at least about 475% the width of thefolded absorbent laminate.

In certain aspects, the longitudinally folded absorbent laminate of anabsorbent core has at least one liquid passageway positioned between thelaminate layers and open to a channel. In certain aspects, thelongitudinally folded absorbent laminate of an absorbent core has atleast two liquid passageways positioned between the laminate layers. Insome aspects, at least one of the two passageways is open to a channel.In certain aspects, the longitudinally folded absorbent laminate of anabsorbent core folded has an interior interfacial area for liquidabsorption that is greater than two times the surface area of the topsurface of the folded laminate.

In certain aspects, the longitudinally folded absorbent laminate of anabsorbent core has incorporated therein free volume articles. In someembodiments, the free volume articles are fibers and DiscreteAcquisition Cells. In other aspects, during use and liquid absorption,the free volume articles provide relatively high free volume within thelaminate to provide better liquid access to the SAP. In some aspects,the Discrete Acquisition Cells are selected from the group consisting ofparticles of compressed cellulose sponge, creped cellulosic paper, soybean hulls, and clumps of fiber such as wood pulp and cellulosic fluffbonded with adhesive, and the fibers are selected from the groupconsisting of continuous filament tow, staple fiber tow, continuousfilament yarn, and staple fiber yarn. In still other embodiments, theabsorbent layer comprises greater than about 40 percent by weight SAP.

In accordance with yet another aspect of the present invention, there isprovided an absorbent core comprising a longitudinally foldedmulti-layer absorbent laminate, the absorbent laminate comprising asubstrate laminate layer and an absorbent layer positioned and adheredon the substrate laminate layer, the absorbent layer containing SAP,wherein the absorbent laminate is folded to form a longitudinally foldedmulti-layer absorbent laminate of at least three layers.

V. BRIEF DESCRIPTION OF THE DRAWINGS

The following drawings illustrate by way of example and not limitation.For the sake of brevity and clarity, every feature of a given structuremay not be labeled in every figure in which that structure appears.Identical reference numbers do not necessarily indicate an identicalstructure. Rather, the same reference number may be used to indicate asimilar feature or a feature with similar functionality, as maynon-identical reference numbers.

FIG. 1 is a schematic view of an absorbent laminate.

FIG. 2 is a schematic view of a multi-layer folded absorbent laminateaccording to one aspect of the present invention.

FIG. 3 is a schematic view of one-half of the multi-layer folded core ofFIG. 2.

FIG. 4 is a schematic view of a 3-layer folded absorbent laminateaccording to one aspect of the present invention.

FIG. 5 is a schematic view of a 4-layer folded absorbent laminateaccording to another aspect of the present invention.

FIG. 6 is a schematic view of a 5-layer folded absorbent laminateaccording to another aspect of the present invention.

FIG. 7 is a schematic view of a multi-layer folded absorbent laminateaccording to another aspect of the present invention.

FIG. 8 schematically illustrates a folded core with a terraced centralchannel comprised of separate layers of laminate encapsulating anoptional acquisition material in the interior of the core.

FIGS. 9A-9E illustrate schematically folding schemes for forming3-layer, 4-layer, 5-layer and 6-layer folded cores.

FIG. 10A is a schematic view of a particular 5-layer folded laminateaccording to an example; 10B illustrates the relation between core widthand channel width for a 533 mm width sheet.

FIG. 11 is a chart reporting the results of a demand absorbencyexperiment performed on a Gravimetric Absorbency Test System (GATS)comparing a multi-layer folded core according to one embodiment of thepresent invention to a sample that does not include the novel featuresof the present invention.

FIG. 12 schematically illustrates an alternate embodiment of amultiple-layer folded core according to the present invention.

FIG. 13 is a schematic cross-sectional view of an absorbent articlecomprising one embodiment of a two-part core according to the presentinvention.

FIGS. 14A-14B are schematic cross-sectional views of absorbent articlescomprising other embodiments of a Two-Part core according to the presentinvention.

FIG. 15 is a chart optimizing the length and width of the ADL tomaximize Mannequin ABL for diapers made with a core of the presentinvention.

FIG. 16 shows dimensions of a 4-layer core after each of two folds.

FIG. 17 illustrates schematically test core structures used for the6-layer and 1-layer SAP AAP tests.

FIG. 18 presents SAP AAP, SAP RUL and SAP EFF results obtained using thecore structures of FIG. 17.

FIG. 19 shows SAP EFF from the 1-layer and 6-layer SAP AAP tests forvarious SAP's over a wide range of CRC.

FIG. 20 shows 0.7 SAP AAP from the 6-layer SAP AAP test for variousSAP's over a wide range of CRC.

FIG. 21 shows SAP CAP results over a CRC range for a 6-layer coreaccording to the present invention.

FIG. 22 shows SAP RUL results over a CRC range for a 6-layer coreaccording to the present invention.

FIG. 23 shows low values of SAP asymmetry and analysis of variance for alaminate in both MD and CD directions.

FIG. 24 shows high values of SAP asymmetry and analysis of variance fora laminate in both MD and CD directions.

FIGS. 25A and 25B present liquid acquisition and rewet test results fora One-Part folded absorbent core compared to two commercially availablediapers.

FIGS. 26A-26B present liquid acquisition and rewet test results for aOne-Part, 6-layer folded absorbent core compared to an unfolded core.

FIGS. 27A-27B present liquid acquisition test and rewet results forTwo-Part, multi-layer absorbent cores according to various embodimentsof the present invention compared to a conventional core.

FIG. 28 presents liquid distribution along a One-Part, folded multilayercore according to the present invention compared to that of aconventional fluff/SAP core.

FIGS. 29A-29B demonstrate liquid acquisition times and rewet values for6-layer folded cores with varying central channel widths.

FIG. 30 shows a one-way Analysis of Variance for absorption times ofSAP's used to make folded, multilayer cores for mannequin tests.

FIGS. 31A-31C relate the effects revealed by Designs of Experimentdetermining the effects of ADL length, ADL width, ADL offset andTackdown Length on mannequin ABL for diapers made with a core of thepresent invention.

VI. DEFINITIONS AND CONSTRUCTIONS

Various features and advantageous details of the present invention areexplained more fully in the following Detailed Description of PreferredEmbodiments section. It should be understood, however, that the detaileddescription and the specific examples, while indicating embodiments ofthe invention, are given by way of illustration only, and not by way oflimitation. Various substitutions, modifications, additions, and/orrearrangements within the spirit and/or scope of the underlyinginventive concept will become apparent to those of ordinary skill in theart from this disclosure.

In the following description, numerous specific details are given toprovide a thorough understanding of the present embodiments. One ofordinary skill in the relevant art will recognize, however, that theinvention may be practiced without one or more of the specific details,or with other methods, components, materials, and so forth. In otherinstances, well-known structures, materials, or operations are not shownor described in detail to avoid obscuring aspects of the invention.

The terms “a” and “an” are defined as one or more unless this disclosureexplicitly requires otherwise.

The terms “absorbent article” and “absorbent garment” refer to garmentsor articles that absorb and contain exudates and, more specifically,refer to garments or articles that are placed against or in proximity tothe body of the wearer to absorb and contain the various exudatesdischarged from the body. These garments or articles, include diapers,training pants, feminine hygiene products, bibs, wound dressing, bedpads, and adult incontinence products. The term “disposable” when usedwith “absorbent article” or “absorbent garment” refers to garments andarticles that are intended to be discarded after a single use.

“Absorbent core” means a structure positioned between a topsheet andbacksheet of an absorbent article for absorbing and containing liquidreceived by the absorbent article and may comprise one or moresubstrates, absorbent polymer material, adhesives or other materials tobind absorbent materials in the core and, for purposes of the presentinvention, includes the disclosed absorbent laminate.

“Absorbent laminate” means the absorbent substrate described hereincomprising top and bottom layers and an absorbent compositiontherebetween.

The terms “comprise” (and any form of comprise, such as “comprises” and“comprising”), “have” (and any form of have, such as “has” and“having”), “include” (and any form of include, such as “includes” and“including”) and “contain” (and any form of contain, such as “contains”and “containing”) are open-ended linking verbs. As a result, a method ordevice that “comprises,” “has,” “includes” or “contains” one or moresteps or elements possesses those one or more steps or elements, but isnot limited to possessing only those one or more elements. Likewise, astep of a method or an element of a device that “comprises,” “has,”“includes” or “contains” one or more features possesses those one ormore features, but is not limited to possessing only those one or morefeatures. Furthermore, a device or structure that is configured in acertain way is configured in at least that way, but may also beconfigured in ways that are not listed. Metric units may be derived fromthe English units provided by applying a conversion and rounding to thenearest millimeter.

The term “coupled” is defined as connected, although not necessarilydirectly, and not necessarily mechanically.

Two items are “couplable” if they can be coupled to each other. Unlessthe context explicitly requires otherwise, items that are couplable arealso decouplable, and vice-versa. One non-limiting way in which a firststructure is couplable to a second structure is for the first structureto be configured to be coupled (or configured to be couplable) to thesecond structure.

Terms such as “first” and “second” are used only to differentiatestructures or features, and not to limit the different structures orfeatures to a particular order.

The term “substantially” and its variations (e.g., “approximately” and“about”) are defined as being largely, but not necessarily wholly, whatis specified (and include wholly what is specified, e.g., substantially90 degrees includes 90 degrees and substantially parallel includesparallel) as understood by one of ordinary skill in the art. In anyembodiment of the present disclosure, the terms “substantially,”“approximately,” and “about” may be substituted with “within [apercentage] of” what is specified, where the percentage includes 0.1, 1,5, 10, and 15 percent.

“Thickness” and “caliper” are used herein interchangeably.

The feature or features of one embodiment may be applied to otherembodiments, even though not described or illustrated, unless expresslyprohibited by this disclosure or the nature of the embodiments.

Other features and associated advantages will become apparent withreference to the following detailed description of specific embodimentsin connection with the accompanying drawings.

VII. DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The present invention is directed to a multi-layer folded absorbent corethat provides numerous advantages, including rapid liquid acquisition,improved core utilization, high superabsorbent material efficiency, theuse of higher capacity superabsorbent materials, excellent liquidcontainment, the possible elimination of conventional materials, such asa core wrap, and improved core stability and integrity in use.

A. The Absorbent Laminate

FIG. 1 is a horizontal cross-sectional illustration of an embodiment ofan absorbent laminate 100 of a type for use in the multi-layer foldedabsorbent core according to the present invention. The absorbentlaminate comprises an upper laminate layer 102, a lower laminate layer104, with an intermediate layer 106 between the upper and lower laminatelayers.

Upper laminate layer 102 and/or lower laminate layer 104 may beconstructed from a variety of materials, including synthetic nonwoven,such as spunbond or carded webs of polypropylene, polyethylene, nylon,polyester and blends of these materials, and tissue. In preferredembodiments, either or both layers comprise tissue. The tissue, forexample, can be a porous tissue, a creped tissue or a standard tissue. Apreferred material is 3995 tissue from Dunn Paper from East Hartford,Conn. The tissue could also be a high creped variety such as 1113, alsoavailable from Dunn Paper.

It is possible to print, or otherwise attach, SAP particles to a singlelayer of tissue or nonwoven and it is envisioned that these types ofmaterials could also be used to make folded, multi-layer absorbent coresthat will be described in later sections. It is well known that thereare non-adhesive bonding methods for laminating tissue and nonwovens.Mechanical bonds or stitching can be used to make bond multi-layertissue laminates. Synthetic fiber nonwovens can be bonded with thermalor ultrasonic bonding techniques well known in the art.

In some embodiments, one or both of upper laminate layer 102 or lowerlaminate layer 104 can comprise a wet strength additive, such as Kymene™from Solenis International, L.P. of Wilmington, Del. Such wet strengthadditive can be applied, preferably in lanes, to the upper and/or lowerlaminate layers in the cross (or width) direction to strengthen theedges and/or control leakage at the side of a folded core. In otherembodiments, upper laminate layer 102, lower laminate layer 104, or bothmay comprise a skin wellness ingredient and/or an odor-controlingredient. In certain embodiments, the upper layer is highly porous andliquid permeable and the lower level is substantially liquidimpermeable.

Turning now to the intermediate layer 106, as mentioned, theintermediate layer includes an absorbent composite comprisingparticulate superabsorbent material 108 and an adhesive composition 110.“Superabsorbent material,” or “Superabsorbent polymer,” or “SAP” refersto water-swellable, water-insoluble material capable of absorbing manytimes its weight in liquid. The superabsorbent material can comprise avariety of materials, including organic compounds, such as cross-linkedpolymers. “Cross-linked” is a commonly understood term and refers to anyapproach for effectively rendering normally water-soluble materialssubstantially water insoluble, but swellable. Such polymers include, forexample, carboxymethylcellulose, alkali metal salts of polyacrylicacids, polyacrylamides, polyvinyl ethers, hydroxypropyl cellulose,polyvinyl morpholinone, polymers and copolymers of vinyl sulfonic acid,polyacrylates, polyacrylamides, polyvinyl pyridine and the like. Othersuitable polymers include hydrolyzed acrylonitrile grafted starch,acrylic acid grafted starch, and isobutylene maleic anhydridecopolymers, and mixtures thereof. Organic high-absorbency materials caninclude natural materials, such as agar, pectin, guar gum and peat moss.In addition to organic materials, superabsorbent materials may alsoinclude inorganic materials, such as absorbent clays and silica gels.Suitable examples of SAP include T9030 from BASF Corporation, Charlotte,N.C.; and W211, W112A, W125 and S125D from Nippon Shokubai Co. Ltd,N.A.I.I., Houston, Tex., and Aqua Keep SA60N II and SA55SX II fromSumitomo Seika Chemicals Co., Ltd., Osaka, Japan.

Over the last 25 years, diaper cores have become thinner and theconcentration of SAP in the core has increased from about 15% in 1990 toabout 50% in 2015. The trend continues today with the commercialintroduction of new types of absorbent cores that contain no fluff pulp.Fluffless cores contain a high basis weight layer of SAP, andliquid-spreading properties of this partially-hydrated, thick layer ofSAP mediate the spreading and distribution of liquid in the core. Underpressure, the spreading of liquid through a swollen gel mass can stop.This condition is referred to as gel blocking To help promote thespreading and distribution of liquid in this type of core thepermeability of SAP's has been increased. SAP permeability is achievedby an increase in crosslinking density that increases the swollen gelstrength of the polymer. Polymers of high gel strength are morepermeable because individual, irregularly-shaped particles of SAP canretain their shape as they swell and prize adjacent particles apart whenswelling under pressure. These swelling particles prize apart, draw airinto the gel mass, and create a capillary network for liquid spreading.SAP's that provide good liquid spreading in a core have higher values of0.7 psi AAP (Absorption Against Pressure) g/g and higher ratios of 0.7AAP/0.7 RUL (ratio of AAP to Retention Under Load) (i.e., SAPEfficiency). The compromise involved in the use of a high gel-strength,permeable SAP is that it has a lower specific liquid-holding capacity,as evidenced by a reduced value of CRC (Centrifuge Retention Capacity),which is expressed in units of g. of liquid absorbed per g. of SAP. Thenet result of these conditions is that more permeable SAP must be usedto achieve the total liquid-holding capacities required for a particularapplication.

Fluffless cores of the current invention provide a multi-layer laminatestructure that separates SAP particles between wicking layers of tissueto greatly reduce gel blocking of the SAP and to promote liquidspreading and distribution between the layers of the laminate. A layerof SAP of about one-particle thickness will be achieved for about 50 gsmof SAP. A SAP layer that has a thickness of two SAP particles thick willbe about 100 gsm. So, even for laminates containing 100 gsm of SAP,individual particles of SAP will be in direct contact with a layer oftissue that provides an effective capillary network for liquidspreading. The capillary network provided by the tissue is, of course,independent of the properties of the SAP and it remains open as the coreabsorbs liquid and the polymer swells. The multi-layer structure of theabsorbent core actually improves SAP performance. It has beenunexpectedly discovered that the structure of a multi-layer core of thecurrent invention imparts exceptional permeability to the core so thatSAP's with higher capacity (and lower permeability) can be used toadvantage to maximize the 0.7 AAP of SAP, and SAP efficiency, in afolded, multi-layer core structure.

Identification of optimal properties of a SAP for efficient use in afolded, multi-layer core is an important part of the current invention.It has been discovered in that regard that SAP's with a mid-range CRC,in the range of about 33-38 g/g, can provide high values of 0.7 AAP,which is a key measure of cost-effective performance in an absorbentcore. 0.7 AAP of preferred SAP's in a multi-layer core have beenmeasured to values of about 23-29 g/g, while the 0.7 SAP AAP for anequal mass of SAP in a 1-layer core has AAP values less than about 20g/g. This is achieved through the use of multi-layer core designs toprovide increases in SAP efficiency under load.

The superabsorbent material typically is in particle form and can be ofany desired configuration, such as granulated powders, fibers,agglomerated spheres and other shapes known to those skilled in the art.The particle size of the superabsorbent material may vary, but typicallyranges from about 20 microns to about 1000 microns. Superabsorbentpolymer particles, however, can impart roughness. According to thepresent invention, a number of ways have been identified to reduce thisroughness. As a first approach, the SAP particle size may be reduced. Ithas been discovered that SAP's for use in the present invention shouldhave a fine particle size distribution. This fine particle size approachcontrasts with state-of-the-art fluffless core design, which generallyuse SAP's with coarse particles to help improve liquid permeability ofhigh gel-strength SAP's. Particularly, superabsorbent polymers having amean particle size in the range of about 250 μm to about 350 μm and witha particle size distribution where only 3% of the mass of thesuperabsorbent polymer cannot pass through a 500 μm screen will providea meaningful reduction in surface roughness of the laminate materials.An example of a superabsorbent polymer with this type of particle sizedistribution would be SA60N Type II provided by Sumitomo. Even morepreferred, surface roughness of the laminate can be mostly eliminatedfor a superabsorbent polymer that contains no particles greater than 500μm.

It also has been discovered that, according to the present invention,this reduction in roughness is largely independent of the basis weightof the SAP used to make the laminates. By way of example, laminates weremade according to the present invention at three SAP basis weights usingthree superabsorbent polymers with two layers of a 17 gsm tissuesubstrate of the grade 3995 commercially available from Dunn Paper fromEast Hartford, Conn. SAP basis weights of the laminates were 47, 60, and97 gsm. The three superabsorbent polymers had different amounts ofpolymer residing in particles greater than 500 μm. SA60N Type II(Sumitomo) had 3% of the mass of the polymer residing in particlesgreater than 500 μm, S125D (Nippon Shokubai) had 18%, and W211 (NipponShokubai) had 48%. W211 provided laminates with the greatest amount ofsurface roughness, S125D provided less roughness, and SA60N Type IIprovided the best laminate with even less roughness. The spherical shapeof particles of the SA60N Type II SAP may have contributed to thereduction in surface roughness. Surface roughness was independent of thebasis weight of SAP used to make these laminates. It was noteworthy thatsurface roughness of the laminates was mostly eliminated when laminateswere made with all of these polymers after the polymers had beenscreened to remove all particles greater than 500 μm.

Alternatively, any commercially available SAP can be used as a startingSAP material and then can be filtered or screened to obtain applicableand useful SAP to minimize surface roughness where the polymer containsless than about 10% of the mass of the polymer residing in particlesgreater than 500 μm, more preferably less than 3%, and most preferablyno particles greater than 500 μm.

In addition to SAP selection or modification, surface roughness may beaddressed by mechanical or structural means, such as by addingadditional tissue or nonwoven or similar material between the laminateand the wearer. For example, laminates containing three and four layersof tissue exhibit less roughness with little or no meaningful increasein core stiffness. Laminates comprised of more than two layers of tissuealso provide better SAP performance, because the total amount of SAPrequired can be placed in more than one layer. SAP efficiency improveswith decreasing SAP basis weight. Placing SAP in more than one layeralso provides opportunities to use more than one SAP, and to use SAP andacquisition materials in separate layers. The basis weight of theexisting tissue substrates can be increased in order to reduce theroughness; however, this approach may not be preferred given the likelyresulting increase in core stiffness. As yet another alternative,Acquisition-Distribution Layers (ADL) of Through-Air-Bonded (TAB)nonwoven in the range of about 30 gsm to about 120 gsm, which is a corestructure well known to those skilled in the art, may be disposed on thesurface of the core adjacent the wearer to mask surface roughness, aswell as improve acquisition and rewet performance. Similarly, cellulosicacquisition fiber layers similarly disposed in the range of about 100gsm to about 350 gsm can mask the roughness. Additionally, TAB nonwovensand cellulosic acquisition fibers can be used together to effectivelyreduce surface roughness.

Additionally, the SAP may be uniformly or non-uniformly distributedwithin the intermediate layer. In the illustrated embodiment of FIG. 1,intermediate layer 106 comprises SAP that is uniformly applied at arelatively low basis weight, thereby forming substantially a singlelayer of SAP particles. However, a non-uniform SAP distribution in theabsorbent laminate is preferred in many embodiments of the invention inorder to enhance z-direction liquid permeability through the laminate.SAP distribution may be reflected by the measured Coefficient ofVariation (COV) of the distribution. COV is defined as the standarddeviation of basis weight of absorbent laminate samples divided by themean basis weight and can be measured according to the following test. Acircular die of 30 mm diameter is used to cut a total of 27 samples froman absorbent laminate according to the present invention. For a 500 mmwide×385 mm length absorbent laminate used to make a folded, multi-layercore, as will be described herein in more detail in subsequent sections,a 3×3 array of samples is cut, in triplicate from three separate piecesof laminate. Each sample is weighed to determine its basis weight, andthe coefficient of variation (COV) of basis weight is calculated for thelaminate. The COV of basis weight is defined as (Std Dev of BW)/(MeanBW)×100%. In preferred embodiments of the present invention, the COV ofbasis weight for absorbent laminates should be greater than about 5%.

As indicated, the intermediate layer of the absorbent composite 106preferably also includes an adhesive composition. The adhesivecomposition should be of a type that is suitable for use in theproduction of disposable hygiene articles. In certain preferredembodiments, the adhesive composition is a thermoplastic hot-meltadhesive composition. A thermoplastic hot-melt adhesive compositiongenerally comprises one or more polymers that provide cohesive strength,a resin or similar material that provides adhesive strength, possiblywaxes, plasticizers or other materials that modify viscosity, and otheradditives, such as antioxidants and stabilizers. According to morepreferred embodiments of the present invention, the adhesive compositionis a pressure-sensitive thermoplastic adhesive composition, morepreferably, a synthetic rubber-based pressure sensitive adhesivecomposition having a glass transition temperature greater than 25° C. Inspecific embodiments, the adhesive composition may be aStyrene-Butadiene-Styrene (SBS) or Styrene-Isoprene-Styrene (SIS) blockcopolymer hotmelt adhesive composition. In this regard, these preferredadhesive compositions are described in Provisional Patent ApplicationNo. 61/946,304, entitled “Novel Absorbent Laminate for DisposableAbsorbent Articles,” filed Feb. 28, 2014, which is herein incorporatedby reference for all purposes and in a manner consistent with thisapplication and invention. The amount of the adhesive compositionapplied should be kept generally at the minimum amount necessary toprovide a laminate with acceptable integrity to be unwound at high speedin a converting process used to make absorbent articles containing thelaminate. In this regard, the preferred adhesive compositions providesufficient cohesive strength to the laminate to allow for the use of areduced amount of the adhesive composition.

The superabsorbent material and adhesive composition may be present inthe intermediate layer in a variety of amounts, with preferredembodiments including the superabsorbent material as the majoritycomponent in the layer. In more preferred embodiments, thesuperabsorbent material comprises at least about 90% of the total weightof the intermediate layer and, more preferably, at least about 94%, evenmore preferably, at least 95%, at least about 97%, at least about 98%and even at least about 99%, of the total weight of the SAP.

In an alternative embodiment the absorbent laminate may utilize discreteacquisition cell (DAC) technology. This technology, and the inventionsrelated to it, are described in U.S. patent application Ser. No.14/212,754, entitled “Absorbent Structure with Discrete AcquisitionCells,” filed on 14 Mar. 2014, and Ser. No. 14/212,969, entitled“Absorbent Structure with Dryness Layer,” filed 14 Mar. 2014, whichapplications are herein incorporated by reference for all purposes andin a manner consistent with this application and invention. DACs addressthe paradox of requiring high free volume for instantaneous liquidabsorption in a low-volume thin structure. DACs provide an instantaneousincrease in free volume in thin cores to rapidly absorb and contain freeliquid before any appreciable swelling of SAP can occur and partitionliquid into SAP over time so as to regenerate free volume in the DACs toabsorb subsequent doses of liquid. Discrete Acquisition Cells can becomprised of compressed cellulosic sponge, creped cellulosic paper, soybean hulls, and other filler materials that provide free volume forrapid absorption of liquid in thin laminates. In other embodiments,filler such as wood pulp or cellulosic fluff, may be mixed with theadhesive and SAP.

In embodiments where the absorbent layer contains Discrete AcquisitionCells, the superabsorbent material comprises at least about 40% of thetotal weight of the intermediate layer. Furthermore, in embodimentswhere the absorbent layer contains continuous filament or staple fibertow, or continuous filament or staple fiber yarn, the superabsorbentmaterial comprises at least about 40% of the total weight of theintermediate layer. In this regard, the basis weight of the SAP in theintermediate layer may range from about 10 grams per square meter (gsm)to about 400 gsm, preferably from about 40 gsm to about 150 gsm.

As shown in FIG. 1, in one embodiment, left edge and right edge oflaminate 100 are open and are substantially uncovered by upper laminatelayer 102 and lower laminate layer 104. In another embodiment, theadhesive extends along at least one longitudinal edge of the laminatesuch that the upper laminate layer is adhered to the lower laminatelayer. In other embodiments, upper laminate layer 102 and lower laminatelayer 104 may be joined together (i.e., adhered or bonded) such thatleft edge and right edge are sealed and absorbent layer 106 is partiallyor totally encapsulated, though, as will be described in the followingparagraphs, such joining is generally not necessary since the laminate,when formed into the multi-layer folded absorbent core, does not exhibitopen edges that could lead to SAP leakage.

The absorbent laminate according to the present invention may bemanufactured according to processes well known to those skilled in theart of absorbent article manufacturing. According to one such process, aroll or sheet of laminate can be made by metering a free-falling curtainof SAP particles and mixing the curtain of SAP particles with hot meltadhesive fibers. This hot melt adhesive fiber curtain can be formedusing conventional hot melt spray equipment, such as the UFD applicatorhead provided commercially by ITW Dynatec in Hendersonville, Tenn.

The resulting mixture is then directed onto a moving substrate (lowerlayer). A second substrate (upper layer) is directed on top of theSAP-adhesive mixture to form a sandwich structure. The fibrous layer ofthermoplastic adhesive may be in at least partial contact with at leastone of the particles of the superabsorbent material, the lower compositelayer and the upper laminate layer. The fibrous layer of thermoplasticadhesive may form cavities in which superabsorbent material particlesmay reside, improving the immobilization of the particles. The fibrousthermoplastic layer may bond to the particles of the superabsorbentmaterial, the lower composite layer or the upper composite layer. Incertain embodiments, the superabsorbent material may be essentiallydispersed throughout the thermoplastic adhesive fibers. The laminate maythen be rolled up and/or cut into segments sized for use in an absorbentarticle. Methods and apparatuses for metering SAP and mixing the SAPwith hot melt adhesive are available commercially and known to thoseskilled in the art.

The laminate of the present invention can also be made to beasymmetrical. “Asymmetry” is defined as the ratio of the weights, orbasis weights, of each of the tissue layers with attached SAP that isobtained upon separation of the laminate. For example, SAP asymmetry isequal to a value of 1 when the SAP is equally distributed between thetwo layers of tissue. Similarly, in a situation in which the laminatehas a total basis weight of 133 gsm (e.g., 97 gsm SAP, 34 gsm tissue,and 2 gsm adhesive), the SAP asymmetry would be approximately 5 if thelaminate were to separate into layers of 111 gsm and 22 gsm. Asymmetrymay be measured by heating a laminate to about 50 C. for about 10 min.and then separating the laminate by peeling the tissue or layers apartand then weighing each side. According to the present invention, SAPasymmetries of greater than about three are preferred, with asymmetriesgreater than about four being even more preferred. In addition,preferred results are obtained when the “weak side” of the laminate ispositioned in an absorbent core, as will be discussed in detail below,to present at the core's surface. One method of manufacturing suchasymmetrical laminates involves applying two mixtures of SAP andadhesive fibers, having different SAP and adhesive contents, to thefirst substrate in two separate layers, one on top of the other.

B. Multi-Layer Folded Absorbent Core

According to the present invention these absorbent laminates may beformed into multi-layer folded absorbent cores that provide novelfeatures and improved performance.

FIGS. 2-8, 10 and 13-14 illustrate schematically various embodiments ofmulti-layer folded absorbent cores according to the present invention.The Figures are exaggerated to better understand the overall structureof the cores and, as such, are for illustrative purposes only and shouldnot be interpreted literally. Specifically, while the Figures show (andthe following discussion of FIGS. 2-8, 10 and 13-14 describe) thesegments as generally horizontal and vertical, with the horizontalportions perpendicular to the vertical segments, such depictions are toillustrate the general folded core structure, the transition from onesegment to another, and the general relationship between the segments,and should not be interpreted to limit the invention. More specifically,while the schematic views, and the following descriptions refer to“vertical” sections, it should be understood that, in application, thedepth dimension, or “Z,” is more compact (see FIG. 9E as morerepresentative of such a structure) and, thus, the “vertical” sectionsappear more as a transition area, or rounded folds, between generallyhorizontal laminate sections. Typical values for the thickness of asingle layer of the laminate and the 6-layer folded core are 0.4-0.5 mmand 2.4-3.4 mm, respectively, measured under a pressure of 2.5 g/cm2. Atypical value for the depth of the central channel is about 2.5 mm.

FIG. 2 schematically illustrates one such multi-layer folded absorbentcore, in this case a 6-layer folded absorbent core 200. Specifically,FIG. 2 is an end view of a schematic illustration of an embodiment of a6-layer absorbent core 200 comprising laminate 100 that has been foldedto form two halves that are symmetrical relative to longitudinalcenterline C and two central channels C1 and C2 that run substantiallythe length of absorbent core 200 along longitudinal centerline C. Thewidth of channel C1 is shown to be greater than that of C2 in FIG. 2,but the widths of C1 and C2 can also be of comparable dimension. Typicalvalues for the thickness of a single layer of the laminate and the6-layer folded core are 0.45 mm and 2.9 mm, respectively, measured undera pressure of 2.5 g/cm2. A typical value for the depth of the centralchannel is about 2.5 mm.

FIG. 3 is a schematic illustration of one-half of 6-layer absorbent core200 shown in FIG. 2 comprising several horizontal and vertical segmentsand forming a folded core. By way of illustration only, each halfcomprises a first horizontal segment 301 adjacent to the longitudinalcenterline C, a first fold 321, a first vertical segment 302 adjacent tofirst horizontal segment 301, a second fold 322, a second horizontalsegment 303 adjacent to first vertical segment 302, a third fold 323, asecond vertical segment 304 adjacent to second horizontal segment 303, afourth fold 324, a third horizontal segment 305 adjacent to secondvertical segment 304, a fifth fold 325, a third vertical segment 306adjacent to third horizontal segment 305, a sixth fold 326, a fourthhorizontal segment 307 adjacent to third vertical segment 306, a seventhfold 327, a fourth vertical segment 308 adjacent to fourth horizontalsegment 307, an eighth fold 328, a fifth horizontal segment 309 adjacentto fourth vertical segment 308, a ninth fold 329, a fifth verticalsegment 310 adjacent to fifth horizontal segment 309, a tenth fold 330,and a sixth horizontal segment 311 adjacent to the fifth verticalsegment 310.

After folding, the six horizontal segments 301, 303, 305, 307, 309, and311 form six layers of folded laminate. In certain embodiments, thelengths of the vertical segments are small compared to the lengths ofthe horizontal segments. Additionally, the vertical segments generallyare in the form of fold, curves or transition areas from one generallyhorizontal segment to another, and not truly vertical segments. This isfurther schematically illustrated in FIGS. 9A-9D and the descriptionrelated to these figures.

Other embodiments of an absorbent laminate may be folded substantiallyas discussed above to form an absorbent core with three, four, or fivelayers as shown schematically in FIGS. 4-6, respectively. For example,laminate 100 may be folded to form an absorbent core 400 with threevertically-positioned layers (FIG. 4); an absorbent core 500 with fourvertically-positioned layers (FIG. 5); and an absorbent core 600 withfive vertically-positioned layers (FIG. 6).

FIG. 7 schematically illustrates yet another embodiment of a multi-layerfolded absorbent core according to the present invention. This coredesign provides enhanced liquid transport through the core by providingpathways or crenellations (internal indentations as will be described infollowing paragraphs) on the out-facing side of the core, in addition tothe pathways from the central channel into the laminate. As can be seen,FIG. 7 schematically illustrates a “terraced” structure at both theouter edges and inner edges of each half of the multi-layer folded core.In alternative embodiments, either of the inner or outer edges may havea uniform edge profile while the opposing edge profile is terraced, orboth inner and outer edge profiles are uniform.

FIG. 8 schematically illustrates yet another embodiment of a multi-layerfolded absorbent core where the opposing terraced edge profile is formedby separate layers of laminate. This core is shown with an optionallayer of acquisition material in the center of the core which is wrappedby the separate layers of laminate. The acquisition material can becomprised, for example, of cellulosic or nonwoven acquisition fiber, orDAC materials of the type previously described.

The multi-layer folded absorbent cores described above may be made onstandard converting machinery of the type typically used in themanufacture of disposable absorbent articles and the folds themselvesmay be made using a folding shoe. Other embodiments comprising differentnumbers of laminate layers are manufactured using this same technique.An example of a typical folding shoe or board used in the industry isdescribed in U.S. Pat. No. 3,401,927, the contents of which areincorporated by reference herein for all purposes and in a mannerconsistent with this application and invention.

FIGS. 9A-9D schematically illustrate, by way of example, the stepsperformed when making 3-layer, 4-layer, 5-layer and 6-layer absorbentcores according to the present invention. To create a 3-layer structure,an absorbent laminate is folded two times. An initial 180 degree fold ismade towards the center line at an axis at each end of the laminate(FIG. 9A). Then, a second 180 degree fold is made at each end in thesame direction as the first fold, at axes closer to the centerline (FIG.9A, second stage). The resultant structure comprises three layers (FIG.9A, third stage).

To create a 4-layer structure, an absorbent laminate is folded threetimes. An initial 180 degree fold is made towards the center line at anaxis at each end of the laminate (FIG. 9B, first stage). Then, a second180 degree fold is made at each end in the same direction as the firstfold at axes closer to the centerline (FIG. 9B, second stage). A third180 degree fold is made at each end in the same direction as the firstfold at another axis that is closer to centerline than each second axisfold (FIG. 9B, third stage). The resultant structure comprises fourlayers (FIG. 9B, fourth stage).

To create a 5-layer structure, an absorbent laminate is folded threetimes. An initial 180 degree fold is made towards the centerline at anaxis at each end of the laminate (FIG. 9C, first stage). Note that theinitial fold can be made in either an up-turned or down-turned manner soas to provide different configurations for the final folded core. Then,a second 180 degree fold in the direction opposite to that of theinitial fold is made at each end at an axis closer to the centerline ofthe laminate (FIG. 9C, second stage). The third 180 degree fold is madeat the axes defined by the ends of the absorbent laminate, in the samedirection as the first fold (FIG. 9C, third stage, dashed lines). Thetopology of the absorbent laminate structure during the third fold(third fold at 90 degrees) is demonstrated (FIG. 9C, fourth stage). Theresultant structure comprises five layers (FIG. 9C, fifth stage).

To create a 6-layer structure, a folded 3-layer structure as describedabove is additionally folded once at each end. An additional 180 degreefold is made at the axis defined by the midpoint of the internal layerat each end, in the same direction as the folds used to create the3-layer structure (FIG. 9D, first stage, dashed lines). The topology ofthe absorbent laminate structure during the additional fold (additionalfold at 90 degrees) is demonstrated (FIG. 9D, second stage). Theresultant structure comprises six layers (FIG. 9D, third stage).

FIG. 9E schematically illustrates the multi-layer folded core of FIG. 9Din its compressed, in use profile.

The multi-layer folded absorbent cores provide significant flexibilityto the selection and content of the SAP in the absorbent laminate and,in turn, in the multi-layer folded absorbent core. For example, asdiscussed above with respect to FIG. 1, laminate 100 may have a SAPbasis weight between about 40 gsm and about 150 gsm in some embodiments.Thus, the basis weight of SAP in a multi-layer folded absorbent corecomprising six layers may range from about 240 gsm to about 600 gsm. Ina preferred embodiment, the laminate has a SAP basis weight of about 60gsm such that 6-layer absorbent core has a SAP basis weight of about 360gsm. Alternatively, the multi-layer absorbent cores providesconsiderable design flexibility for adjusting core structure and anoverall SAP basis weight. For example, to make a core with a total SAPbasis weight of about 360 gsm, the absorbent laminate layer may have aSAP basis weight of about 120 gsm in a three-layer absorbent core, a SAPbasis weight of about 90 gsm in a 4-layer absorbent core, and a SAPbasis weight of about 72 gsm in a 5-layer absorbent core.

In certain embodiments, the vertical segments may bow or bend toward oraway from centerline C. As mentioned previously, one of skill in the artwould understand that a “fold” or “vertical” section is a location oftransition between two generally horizontal segments and does notnecessarily require a crease or other abrupt transition.

Returning to FIG. 2, the width of the channel(s) may vary along thecore's thickness or caliper. In this regard and according to FIG. 2,first channel C1 is formed between opposing second vertical segments 204and second channel C2 is formed between opposing fourth verticalsegments 208. As shown in FIG. 2, first channel C1 may be wider thansecond channel C2 (C1>C2), providing a central channel with a greaterwidth at the surface of the absorbent core 200; however in otherembodiments, first channel C1 may be generally the same width as secondchannel C2 (C1=C2). In some embodiments of the current invention, thewidth of second central channel C2 can be <10 mm to provide moreabsorbency in the center of the core, and the width of first centralchannel C1 can be greater than one-half of the width of the folded core.When first central channel C1 is wide, acquisition material 250 in FIG.2 may be a formed pad comprised of cellulosic acquisition fiber.Furthermore, when this pad of acquisition fiber is encased in a corewrap of tissue or nonwoven, and its width is somewhat less than that ofcentral channel C1, additional central channels for liquid absorptioncan be formed by gaps between the sides of wrapped pad 250 and verticalsections of laminate 204.

Importantly for purposes of the present invention, the channel should bewide enough so as not to close during swelling of the absorbentlaminate. An open channel provides improved and advantageous liquidacquisition time and rewet performance. As known to those skilled in theart, liquid acquisition time is the time for a section of absorbent toabsorb a known volume of liquid, typically saline, and rewet is theamount of liquid returned to the surface of the absorbent onto anabsorbent filter paper when the absorbent is compressed by an externalload. In certain preferred embodiments, the width of first channel C1and/or second channel C2 should be at least about 2 mm, and morepreferably at least about 8 mm. In more preferred embodiments, thechannel's width is between about 8 mm and about 50 mm, more preferably,between about 15 mm and about 20 mm. Widths in this range compensate forthe occasional “ruck” or overlap between the sides of the channel due inpart to pressure applied to the sides of the core by the wearer.Additionally, swelling of the SAP in the laminate during liquidabsorption further reduces the width of the channel and, thus, reducesperformance. For cores having a folded width of 80-120 mm, the channelshould preferably be between about 5% and about 45% of the folded corewidth and more preferably between about 8% and about 20%. For example,in FIG. 10A, absorbent laminates with a width of 533 mm can be formedinto a 5-layer absorbent core of 115 mm width with a central channelwidth of 10 mm. In this example, the width of the parent laminate is463% of the width of the folded core. According to another example, anabsorbent laminate with a width of 533 mm can be formed into a 6-layerabsorbent core of 100 mm width with a central channel width of 9 mm or a6-layer core of 115 mm width with a central channel width of 15 mm. FIG.10B shows experimental data for channel width as a function of corewidth for 6-layer folded cores made with a single layer of laminate thatis 533 mm in length.

Also importantly, such a multi-layer folded absorbent core constructionincreases the surface area of the absorbent laminate 100 that may beexposed to exudates and liquids (i.e., the interfacial area). Forexample, in certain embodiments, the novel folded geometry of absorbentcore 200 provides internal surfaces that provide surface area of atleast twice the geometric surface area (i.e., the footprint) of thefolded absorbent core. In other embodiments, the interfacial area can beat least three times, at least four times, at least five times, at leastsix times, or more the geometric surface area.

In addition to the multi-layer folded geometry of the absorbent cores ofthe present invention, a key feature of the invention involves theimproved and unexpected liquid acquisition and distribution provided bythe central channel and internal liquid passageways, includingcrenellations formed by the folding of the absorbent laminate. A liquidpassageway refers to any means for liquid movement in the multi-layercore, including the internal crenellations. As noted previously, acrenellation is an internal indentation or crevice for liquid movement.Discussing first the central channel, the central channel provides amechanism for receiving and containing large volumes of liquid (surges)and directing the bulk flow of liquid both longitudinally along the coreand laterally within the core. As a result, core utilization is improvedover that of a conventional fluff/SAP core that spreads liquid via aradial wicking mechanism. Furthermore, liquid travel in the inventivecore is enhanced by the multiple liquid passageways presented. Theinternal crevices or interfaces are an important element of such liquidmovement. The internal crevices or interfaces further enhance coreutilization by moving laterally and longitudinally liquid from thecentral channel along and between the layers to significantly increaseintroduction of liquid to the larger interfacial core area. Such amechanism is not burdened by the slower rate of liquid diffusion throughthe absorbent laminate in the z (top-to-bottom)-direction. In anotheradvantage of the inventive design, the channels and spaces between thefolds create spaces where exudates and liquids may be contained untilthey can be absorbed into the absorbent layer. Note that 3- and 4-layerfolded cores have only one crenellation on each side of the centralchannel, whereas 5- and 6-layer folded cores in FIGS. 2 and 6 have twocrenellations on each side of the central channel. As a result, 5- and6-layer folded cores generally provide superior liquid acquisition speedas a result of the doubling of this internal surface area. An advantageof the “Christmas tree” fold design, such as the design of FIG. 7, isthat it provides multiple crenellations open to the central channel, aswell as additional crenellations which are open to the side of the core.An advantage, in general, for multi-layer cores of this invention isthat there is much less side leakage, measured in laboratory liquidacquisition/rewet tests, because less liquid moves in a radial patternat the center of a folded, multi-layer core. Preferably, according tothe invention, the central channel or channels and crenellations providean internal or interfacial surface (the laminate-to-laminate interfaceswhich provide a path for liquid spreading) that is greater than twotimes the surface area of the laminate without the channel(s) andcrenellations.

To determine the impact on liquid acquisition and distribution of thecentral channel(s) and crenellations, a demand absorbency experiment wasperformed to compare a 6-layer folded core with crenellations and acentral channel to 6-layers of the same absorbent laminate withoutcrenellations and central channel. Demand absorbency is measured using aGravimetric Absorbency Test System (GATS). According to this testprotocol, a 60 mm diameter sample was cut from an absorbent core. Suchcuts were made using a circular die and a clicker press, for example.During a measurement, a sample was restrained by a 60 mm diametersection of rigid tubing. A positive hydrostatic tension of about 1 mmwas provided through a 5 mm single aperture centered in a solid plate.The sample was centered on the plate over the aperture under a loadproviding a pressure of 0.3 psi. Results were expressed as g/g of sampleas a function of time. Rates of absorption were calculated from theslopes of this absorption curve. The results of the demand absorbencytest are shown in FIG. 11. As a result of liquid spreading within theinterior of the core via the crenellated surfaces connected to thecentral channel, the volume of liquid absorbed by the folded core withthe central channel was greater than 3× the volume of liquid absorbed by6-layers of the laminate without a central channel and crenellationsafter 10 minutes.

FIG. 2 also illustrates that the central channel may include an insert250 to improve liquid acquisition performance and reduce end leakage (ithas also been determined that after liquid absorption slows after thefirst few doses, the insert can impede bulk liquid flow along thecentral channel to reduce or eliminate leakage from the front or rear ofthe core through the central channel.) The channel may include two ormore inserts in those cases in which the width of the channel changesalong the thickness or caliper of the core. The inclusion of an insertor inserts in the central channel may mean that a conventionalAcquisition Distribution Layer, or ADL, on the surface of the core isnot as important for the multi-layered cores of this invention as it isfor conventional fluff/SAP cores and current fluffless cores.

In certain embodiments, channel insert 250 is about the same width asthe channel into which it is inserted (i.e., first channel C1 or secondchannel C2). Additionally, in certain embodiments, channel insert 250 isat least about half the depth of the channel into which it is inserted(i.e., first channel C1 or second channel C2). It is possible to have aninsert reside both in the central channel and a portion of an internalcrenellation, such that the insert is wider than central channels C1 andC2, but not as wide as the width of the folded core.

The insert can comprise an ADL-like nonwoven insert, which exhibitsadvantageous properties of acquiring the liquid insult and releasing anddistributing the liquid across a broader area. More specifically,channel insert 250 may comprise a through-air bonded, or TAB, ADL,preferably comprised of bicomponent fibers that had been treated with adurable or nondurable hydrophilic surface finish. In other embodiments,channel insert 250 may comprise melt-blown polypropylene or a low-twistyarn. In the case of low-twist yarns, the yarn may be comprised ofpolyester continuous filament or staple fibers with a durable, oralternatively non-durable, hydrophilic finish and, specifically, mayrange from about 1000 decitex to about 1500 decitex. In yet anotherembodiment, the channel insert may be a continuous filament or staplefiber tow or narrow-slit nonwoven carded or spunbond pulled from end ofa spool to make a twisted, ribbon-like structure. In one embodiment, theinsert is a 60 gsm TAB ADL having a width of between about 5 mm and 15mm. In an alternative embodiment, the insert may utilize discreteacquisition cell (DAC) technology. As previously noted, DiscreteAcquisition Cells can be comprised of compressed cellulosic sponge,creped cellulosic paper, soy bean bulls, and other filler materials thatprovide free volume for rapid absorption of liquid in thin laminates.The DACs can be incorporated into the crenellations of a folded core orintroduced into the core in an absorbent laminate.

In yet further embodiments, channel insert 250 may comprise a cellulosicacquisition fiber. The cellulosic acquisition fiber may further compriseSAP. In preferred embodiments, the cellulosic acquisition fibercomprises no more than about 10% by weight SAP. A layer of cellulosicacquisition fiber could also be placed on the surface of a multi-layerfolded core. A conventional (fiber or film) ADL is usually required onthe surface of cellulosic acquisition fiber to improved overall drynessof the core.

In an alternative folding geometry according to the present invention,the multiple folded core may be inverted with the opening of the centralchannel facing away from the wearer. A single layer of laminate coveringthe central channel with the core in an inverted position has sufficientporosity for the central channel and absorbent core to provide rapidliquid acquisition and spreading.

In still yet another embodiment, a sprayable adhesive, a wet-strengthresin, or other material could be applied selectively to the outer edgesof a multi-layer core to impart wet strength to the tissue.

In yet another embodiment as shown in FIG. 12 and FIG. 8, amultiple-layer absorbent core is achieved by stacking multiplelaminates, which are then folded into a C-fold configuration. In acertain embodiment, the single-step C-folding of the stacked multiplelaminates, each with identical dimensions, achieves a tapered centralchannel as shown in FIG. 12. This embodiment is beneficial as thefolding occurs in a single step and has the added benefit of suppressingthe feel of the edges of the channel as the channel is only three layersthick and the edges taper outwardly. In addition, the wider opening of atapered or terraced central channel helps liquid to flow into theinterior of the core when that liquid impinges the surface of the coreat a distance from the center of the open channel.

C. One-Part and Two-Part Multi-Layer Folded Cores

Turning now to another aspect of the invention, the multi-layer foldedcore according to the present invention may be used as the soleabsorbent core in an absorbent article (a “One-Part” core) or may becombined with a second core (a “Two-Part” core). The second core may bea single layer absorbent laminate, one or more other multi-layer foldedcores, a conventional (SAP/fluff or fluff only) absorbent core, orcombinations thereof. Two-Part cores provide zoned absorbency toincrease absorbency in a part of the product where absorbency is needed.Two-Part absorbent cores are well known in the industry for optimizationof performance and raw material cost.

FIG. 13, FIG. 14A and FIG. 14B schematically illustrate embodiments ofabsorbent articles that comprise Two-Part absorbent cores. According tothe embodiment shown in FIG. 13, an absorbent article 1000 comprisestopsheet 1001, a first multi-layer folded core according to oneembodiment of the invention, which will be referred to as a “surge” core1002, optional channel insert 1003, a second multi-layer folded coreaccording to the present invention, which will be referred to as a“base” core 1004, and a backsheet 1005.

In the illustrated embodiment, surge core 1002 additionally comprises alayer of cellulosic acquisition fiber 1016 positioned above themulti-layer folded core itself to improve liquid acquisitionperformance. Cellulosic acquisition fiber has a higher AbsorptionAgainst Pressure (“AAP”) value and a lower Centrifuge Retention Capacity(“CRC”) value than that of fluff pulp. AAP and CRC are parameters wellknown to those skilled in the disposable absorbent article field. TheAAP test method is described in EDANA WSP 242.3 (10), and the CRC testmethod is described in EDANA Test Method WSP 241.2.R3 (12) bothincorporated herein by reference. AAP is a measure of an absorbentmaterial's ability to absorb a 0.9% saline solution against a 0.7 psiload. CRC is a measure of the amount of 0.9 wt % saline solution that anabsorbent material can retain after free swell and centrifugation toremove bulk interstitial liquid. The acquisition fiber layer 1016absorbs liquid rapidly, temporarily holds it with capillary tension, andpartitions the liquid over time to the core below. Cellulosicacquisition fiber is well known to those skilled in the art. In analternative embodiment, a layer of cellulosic acquisition fiber can beplaced into the central channel to improve liquid acquisitionperformance. This acquisition fiber, in both cases, can be used with orwithout SAP and, if SAP is included, levels of about 10% or less arepreferred.

In an alternative embodiment, conventional (fiber- or film-based) ADLcan be placed on the top surface of the folded surge core to provideadditional dryness. Similar to the cellulosic acquisition fiber, the ADLcan be folded within a multi-layer folded core to impede rapid spreadingof high volumes of liquid in the central channel. Additionally, the ADLcan assume a variety of widths and lengths depending on, among otherparameters, the core width. In general, ADL widths approximately equalto the width of the multi-layer core, or at least about 95% of the corewidth, are preferred. FIG. 15 shows an example of the effect of ADLwidth and length on a 6-layer core made with a laminate containing 97gsm SAP. When the ADL had a width of 110 mm, i.e., equal to the width ofthe core, the mannequin leakage performance was good and independent ofthe length of the ADL over a range of 149-197 mm. However, for an ADLwith a narrower width of 90 mm., i.e., only 82% of the core width,mannequin leakage performance became poorer as the ADL length wasdecreased from 197 to 149 mm.

It also has been determined that placement of an ADL relative to thefront edge of the absorbent core (known as “offset”) affects overallleakage. In this regard, preferred performance has been discovered whenthe ADL is offset from the core's front edge. For example, coresaccording to the present invention exhibited reduced leakage resultswhen the ADL is offset from the core's front edge, by at least about 25mm and, in some cases, at least about 50 mm or greater.

Absorbent articles, particularly baby diapers, oftentimes includestand-up barrier cuffs that reduce side leakage in use. These cuffs aregenerally adhered or “tacked down” at their ends to the wearer-sidearticle surface. It has been discovered in accordance with the presentmulti-layer core design that leakage results are affected by theposition of this tack down relative to the core's front edge.Particularly, it has been discovered that improved leakage results areobtained with the novel core designs of the present invention when thebarrier cuff is free-standing along the length of the core and is tackeddown approximately at the front edge of the core, but not overlaying thecore itself.

FIG. 13 also shows schematically that the absorbent cores 1002 and 1004are enclosed and retained by a wrap material 1012 and 1014. Core wrapsare well known in the art and may be constructed from, for example,tissue or nonwoven material. However, because of the excellent corestability of the multi-layer folded cores of the present invention, itwill be possible, and in many cases preferable, to use a multi-layercore in an absorbent product without any additional tissue or nonwovencore wrap.

It has further been determined that the leakage performance of cores ofthe current invention can be improved by selection of a SAP that has anoptimal liquid absorption time for the particular dimensions of thecore. For example, SAP's with a 0.9% saline absorbency time in the rangeof about 160 seconds to about 220 seconds provide improved absorbencybefore leakage in a baby diaper than SAP's with absorption rates belowabout 160 seconds. A test method used to determine the relevantabsorption times of SAP's will be described in a later section.

Additionally, in a preferred embodiment, zoned absorbency may beimplemented in a Two-Part core to make efficient use of the absorbentmaterials. More specifically, in a Two-Part core, the surge layer may beshorter than the base core to provide more absorbent material andabsorbency in the area of insult and less core and absorbency in areasof less insult and liquid. For example, in a specific embodiment, thebase core may be about 80 to about 120 mm wide and about 345 to about400 mm long, while a surge core may be about 80 to about 120 mm wide andabout 215 to about 260 mm long. In yet another embodiment of a Two-Partcore, shown in FIG. 14B, the partial length surge core is comprised of afolded, multi-layer core (in this example a 6-layer core) that has afolded width that is about 20 mm less than the width of the centralchannel formed by a folded, multi-layer core (in this example a 3-layercore) of the lower, full length base core. This core presents threecentral channels to a wearer of the absorbent article containing thecore. This embodiment is particularly effective at acquiring liquid thatmight impinge the core to one side of the central channel formed by thesurge core and run off to the side of the product, such as when theabsorbent article is being used with the subject lying on their side.These configurations are all envisioned to fall within the scope of thepresent invention.

Also, Two-Part cores can be made with different SAP's in each core. Forexample, a more permeable SAP may be included in the upper, or surge,core laminate for improved liquid acquisition and a higher capacity SAPmay be included in the lower, or base, core laminate for higher liquidcapacity. Alternatively Two-Part cores can be made with an upper, surgelayer comprised of a multi-layer absorbent core containing a highercapacity SAP and a lower, base layer comprised of a lower capacity,slower absorbing, higher permeability SAP to improve spreading and coreutilization. It is advantageous to include acquisition materials andDAC's in the laminates used to make the surge core.

FIG. 14A is a schematic cross-sectional view of another embodiment of anabsorbent article 1100 having a Two-Part core. As shown in FIG. 14A, thecore comprises topsheet 1101, surge core 1102, channel insert 1103, andbacksheet 1105. According to this embodiment, the base core 1104comprises a C-folded layer of absorbent laminate located below surgecore 1102. The C-fold will seal the laminate edges to the backsheetunder itself and eliminate migration of hydrated SAP from the free endsof the laminate. This, however, is usually not necessary as that SAP iswell-constrained within the laminate. An ADL 1106 is located above surgecore 1102 and channel insert 1103. In other embodiments, base core 1104may be a single unfolded layer. In yet additional embodiments, base core1104 may comprise a mixture of conventional fluff and SAP, or maycomprise only conventional fluff.

Similar to Two-Part cores, a One-Part core would include the standardtopsheet and backsheet, and possibly an ADL, as schematicallyillustrated in FIG. 13 and FIG. 14A for Two-Part cores, however,obviously utilizing only one multi-layer absorbent core. Such one-partcores may offer better manufacturing on a converting machine.

In both One-Part and Two-Part absorbent cores, the geometry anddimensions of the core or cores may vary. For example, in an embodimentconfigured for use in a baby diaper, a One-Part core may be betweenabout 200 mm and about 450 mm, preferably between about 345 mm and about385 mm, long, between about 60 mm and about 120 mm, preferably about 110mm wide, and between about 2 mm and about 6 mm, preferably about 3.1 mmin thickness or caliper. In a preferred embodiment of a Two-Part core,the upper surge core is from about 215 mm to about 245 mm long. Thefolded width of the surge core would be about 100 mm wide and about 3.8mm in thickness or caliper. The base core is from about 345 mm to about385 mm long and from about 100 mm to about 120 mm wide. The lower basecore of this preferred embodiment could be made from either a foldedlaminate or a single layer of unfolded laminate. The preferred thicknessor caliper of combined upper and lower cores of this Two-Part core wouldbe about 4 mm.

The folded core of the present invention is in most embodiments greaterthan 2 mm in thickness. It is formed, however from a material that ismuch thinner. By way of example, a 1066 mm diameter roll of the laminatewill yield at least 3100 lineal meters of material. Such a roll wouldyield over 8500 cores and, if it were running at a production rate of400 products per minute, would run for longer than 21 minutes. Roll runtime over 15 minutes is considered not unreasonable for those skilled inthe art. This would not be possible if the core had to be unwound from aroll in its final thickness and, thus, presents a serious problem forcore technologies that require that cores be unwound from their rolls intheir final thickness.

Core placement within the absorbent article also is important.Particularly, preferred embodiments place the leading edge of the corewithin about 30 mm, and preferably less, of the front edge of the diaperchassis. Another relative measure regarding the placement of the core isits location relative to the frontal tape that is often part of anabsorbent article's design. Preferably, the leading edge of the core ispositioned slightly behind the frontal tape relative to the absorbentarticle's front edge.

Preferred embodiments for the Two-Part core design, include (a) a6-layer surge core comprising 45-97 gsm S125D SAP per layer and having alength of 215 mm combined with a single-layer absorbent laminatecomprising 89 gsm W211 SAP and having a length of 345 mm; (b) a 5-layersurge core comprising 45-97 gsm W125 SAP per layer and having a lengthof 215 mm combined with a single layer absorbent laminate comprising 97gsm W125 SAP and having a length of 385 mm; and (c) a 5-layer surge corecomprising 45-97 gsm SA55SX II SAP per layer and having a length of 215mm combined with a folded, 2-layer absorbent laminate comprising 89 gsmSA55SX II SAP and having a length of 385 mm. In each case, both surgeand lower cores have a folded width of about 110 mm and a centralchannel having a width in the range from about 10 to about 20 mm.

Preferred embodiments for the One-Part core design, include (a) a6-layer core comprising about 45-97 gsm S125D SAP per layer, (b) a5-layer core comprising 45-97 gsm W125 SAP per layer, and (c) a 5-layercore comprising 45-97 gsm SA55SX II SAP per layer. The core has a lengthof from about 345 mm to about 385 mm, a width of about 110 mm, and acentral channel width of from about 10 mm to about 20 mm.

The multi-layer folded cores of the present invention may bemanufactured using conventional converting equipment. For example, largepancake rolls can be utilized to handle the absorbent laminate, thusavoiding the need for expensive separate processes for spooling orfestooning. Similarly, the laminate can be folded in a relativelystraightforward process, for example, by use of a folding shoe, or inother ways that will be well known to those skilled in the art. Theprocess experiences little to no SAP loss during conversion because theSAP is confined between tissue or nonwoven layers. Additionally, theprocess offers ample opportunity to increase line speeds on an off-linelaminate process to reduce raw material cost. Alternatively, it may bepossible to reduce cost by making the laminate for the multi-layer coreon-line.

The multi-layer folded absorbent cores of the present invention and theabsorbent products that incorporate these cores present improved andunexpected results when compared with conventional cores. For example,the multi-layer cores exhibit improved liquid acquisition resulting fromthe central channel, crenellations, high internal surface area, andwicking between adjacent upper and lower layers. Additionally, the coresexhibit good core utilization with the central channel moving liquid inlongitudinal and lateral directions and improved core stability andintegrity in use.

The cores of the present invention display high SAP efficiency due tothe low SAP basis weight in the individual layers of laminate and allowthe use of higher capacity SAP's with moderate permeability. Morespecifically, high absorbency against pressure (AAP) and high SAPefficiency in a multi-layer laminate can be obtained with superabsorbentpolymers of higher centrifuge retention capacity (CRC) than canotherwise be used in thin cores without fluff pulp. For example, apreferred SAP may exhibit a CRC value of about 33-38 g/g. Similarly,preferred SAP's exhibit a Saline Flow Conductivity (SFC) value betweenabout 0 and about 10×10-7 cm3 sec/g. Saline Flow Conductivity, anothermeasure well-known in the disposable absorbent article field anddescribed, for example, in U.S. Pat. No. 5,599,335, measures thepermeability of a swollen hydrogel layer.

The multi-layer structure of the absorbent core improves performance ofthe SAP. For example, six layers of laminate each comprised of 54 gsm ofW211 SAP (an absorbent material with a relatively low AAP and high CRC)had an 0.7 psi AAP of 12.9 g/g. Adjusting for the contribution of twelvelayers of the tissue in the laminate, the 0.7 psi AAP of the SAP alonewas calculated to be 18.3 g/g. The 0.7 psi AAP of an equal basis weight(i.e., 324 gsm) of W211 SAP in a single layer was measured to be only9.1 g/g. Thus, the 0.7 psi AAP of the SAP was doubled when incorporatedinto a multilayered core structure. More generally, the 0.7 psi AAP ofthe SAP in multi-layer absorbent cores according to the presentinvention is greater than 1.5 times the 0.7 psi AAP of the same totalbasis weight of SAP in a single layer. The ability to successfully usesuperabsorbent polymers with relatively low AAP and high CRC in theabsorbent cores of this invention contrasts with current pulpless coredesigns which have used superabsorbent polymers with relatively highAAP, low CRC and high permeability (i.e., SFC>20×10-7 cm3 sec/g). Asuperabsorbent polymer with high values of SFC and 0.7 AAP has arelatively low CRC capacity, and more of this type of SAP will be neededto provide the liquid capacity required of an absorbent core tofunction.

In addition, the cores have excellent liquid containment, exhibiting noside leakage in testing. The cores offer manufacturing advantages aswell. Specifically, they can be produced with moderate run times and byuse of simple folding equipment well known in the art. Also, theinventive cores experience manufacturing savings in that they do notrequire a nonwoven core wrap.

In still another advantage, the multi-layer absorbent cores exhibitdecreased thickness or caliper when compared to conventional fluff/SAPcores, as well as newer fluffless cores. This is true even for 6-layercores according to the present invention. The thinner cores of thepresent invention have advantages for making more discreet, garment-likeabsorbent products that require less packaging and can be stored andshipped at lower cost. Caliper measurements of diaper cores, obtainedunder a restraining pressure of 2.5 g/cm2, are shown in FIG. 16. AOne-Part, folded 6-layer core made with a laminate containing 45 gsm ofSAP had a thickness of only 3.1 mm. A Two-Part core with an upper layercomprised of 6 folded layers of a laminate containing 60 gsm of SAP anda lower layer comprised of a single layer of laminate containing 89 gsmof SAP had a thickness of 3.8 mm. In both cases, the thicknesses werematerially thinner than commercially available products containing aconventional fluff/SAP.

Improved aspects of liquid acquisition and rewet, mannequin leakageperformance, and core stability of folded, multi-layer cores will bedescribed in more detail in the Experiments section, which follows.

VIII. EXEMPLARY EMBODIMENTS Example 1

A laminate was produced by providing a continuous moving substrate of 17gsm 3995 tissue, which, for example, is commercially available from DunnPaper in East Hartford, Conn. A first layer of 30 gsm W125 SAP, which,for example, is commercially available from Nippon Shokubai was mixedwith 1.3 gsm SP507 hot melt glue fibers, which, for example, iscommercially available from Savare in Delaware, Ohio, to form a firstmixture. The 1.3 gsm SP507 hot melt glue fibers was dispensed by UniformFiber Deposition (UFD) hot melt spray head from ITW Dynatec inHendersonville, Tenn. A second layer of 70 gsm SAP was mixed with 1.6gsm hot melt glue fibers to form a second mixture. The second mixturewas deposited on top of the first mixture, and a second continuousmoving substrate of 3995 tissue was placed on top of the hot meltadhesive. The resulting laminate was wound into a roll and comprised SAPasymmetry exceeding 3:1.

A size 4 diaper was produced using the Example 1 laminate. The laminatewas slit to a width of 533 millimeters and folded into a 5-layer core ona commercial diaper machine using folding boards. FIG. 10A depicts oneexample of the 5-layer core fold that was used in this example. Theresulting core comprised a width of approximately 110 mm (e.g., from 90to 120 mm), a length of approximately 363 mm (e.g., from 350 to 400 mm),and a central channel width of approximately 10 mm (e.g., from 5 to 15mm). The core was positioned approximately 28 mm from the front of thediaper. The acquisition layer comprised a width of approximately 108 mmand a length of approximately 149 mm. The approximate position of theADL was 50 mm from the leading edge of the core. The elastic tack downwas approximately 10 mm from the leading edge of the core. The end ofthe elasticated length was approximately 10 mm from the front of thediaper. The Average Mannequin ABL was approximately 243 ml. Theremainder of the chassis was the same as the control product that iscommercially available with a conventional fluff/SAP core.

Example 2

A laminate was produced in a similar manner to that described inExample 1. A However, a W211 SAP type was used. Further, rather than twoplies of substrate, three plies of 3995 tissue was used. Between eachtissue layer was disposed a layer of a mixture of 23.5 gsm SAP and 1.3gsm SP507 adhesive. The Example 2 laminate was made into a diaper in thesame or a substantially similar manner as the laminate in Example 1.

One-Part Cores having six layers were constructed with absorbentlaminates of 89 gsm S125D SAP and 47 gsm W211 SAP. These six-layer coreswere made with a laminate of approximately 385 mm in length andapproximately 533 mm in width (e.g., and only approximately 513 mm SAPin width). The width of the folded core was approximately 98 mm, and thewidth of the central channel was approximately 10 mm. Measured values ofAAP were greater than predicted from SAP properties because of acore-structure-induced increase in SAP efficiency. The folded coregeometry with the central channel and internal crenellations providedimproved core utilization to enhance performance at a reduced level ofSAP. An examples of an additional embodiment is depicted in FIG. 16.

IX. EXPERIMENTS

A. Absorbent Laminate

1. SAP Properties for Optimal Absorbency of Multi-Layer Laminate

As discussed in preceding paragraphs, an absorbent laminate of the typedescribed herein has provided evidence of structure-induced improvementsin SAP efficiency in a multi-layered absorbent core. Specifically,Absorption Against Pressure (AAP), Capacity (CAP) and Retention UnderLoad (RUL) were measured for six layers of an absorbent laminate, usingthe Domtar Personal Care test method described below, and compared tovalues obtained for a single layer of the same total amount of SAP. Themethod is a modified version of EDANA WSP 242.3 (10) Worldwide StrategicPartners EDANA (European Disposables and Nonwoven Association, AvenueEugene Plasky, 157, 1030 Brussels, Belgium, www.edana.com), which isincorporated herein by reference. Six layers of this absorbent laminateat this basis weight provide the necessary absorbency for an infantdiaper. According to the test methodology, a “6-layer” sample of amulti-layer laminate was constructed. This 6-layer sample comprised sixvertically stacked laminates, each laminate comprised of 0.15 g. SAP anda single layer of tissue placed above and below each layer of SAP. Eachsample of multi-layer laminate, therefore, contained a total of 12layers of tissue and 6 layers of SAP. For comparison, a more typical1-layer sample was made using the same mass of absorbent materials byplacing the total 0.9 g. of SAP between six layers of tissue above andsix layers of tissue below the single layer of SAP, as shownschematically in FIG. 17. The more typical 1-layer core structure for apulpless core is referenced in FIG. 17 as “A” and the 6-layer absorbentlaminate structure is referenced as “B.”

Pursuant to Domtar Personal Care test method for Absorption AgainstPressure (AAP) test, a sample was placed in a holder or cell and testswere performed by following absorption of the samples in 0.9% salineunder a load of 0.7 psi, followed by removing the 0.7 psi load andre-weighing the cell and hydrated sample to obtain Capacity (CAP) in anunloaded, free swell condition, then followed by replacing the 0.7 psiload on the hydrated sample in the cell to obtain Retention Under Load(RUL). Saline solution for the tests was purchased from Lab Chem Inc.,Cat. No. 07933, which had a specification of 0.9% Wt./Vol.±0.005% sodiumchloride. AAP and RUL were measured under a pressure of 0.7 psi, whereasCAP was measured using no load. SAP efficiency was calculated asAAP/RUL×100%. The SAP efficiency was expressed taking into account thecontribution of the tissue (measured in a separate experiment) so as toprovide a measure of absorbency that can be attributed to the SAP alone,i.e., SAP 0.7 AAP. Values of 4.6 g/g, 6.0 g/g, and 5.0 g/g were used,respectively, for the 0.7 AAP, CAP, and 0.7 RUL of the tissue. Note that0.7 RUL provides a measure of the maximum possible value of 0.7 AAP,because 0.7 RUL does not depend materially on the permeability of thepolymer. The ratio of AAP/RUL, or SAP efficiency, provides a measure ofinefficiency in absorption due to a lack of permeability of the sample.

Results are presented in FIG. 18. SAP AAP and SAP efficiency (SAP EFF)for the 6-layer sample increased significantly over that of the 1-layersample for the SAP's that had mid-range values of permeability,expressed as a Saline Flow Conductivity (SFC) greater than 0 and lessthan 10 (×10-7 cm3 sec/g). For example, SAP 0.7 AAP for S125D increasedfrom 14.4 g/g to 23.2 g/g and SAP EFF increased from a value of 48% to71%. The SAP efficiency of 6-layer samples made with the S125D polymerwere significantly increased by the core structure of the presentinvention, and provided a high value of 0.7 psi AAP.

Centrifuge Retention Capacity (CRC), not measured here, is universallyavailable from manufacturers of superabsorbent polymer. EDANA TestMethod WSP 241.2.R3 (12) involves centrifugation of a fully saturatedpolymer (with 0.9% saline) at a force equal to a centrifugalacceleration of 250±5 G for 3 min.±10 sec. CRC is a good measure of theliquid-holding capacity of a superabsorbent polymer.

Superabsorbent polymers that are preferred for use in a 6-layer laminateare those capable of generating high values of 0.7 AAP at the highestpossible value of CRC. Using the AAP test methodology previouslydescribed, it has been possible to identify the properties of preferredSAP's for use in a multi-layer core.

Testing of many superabsorbent polymers has shown that the SAP EFF ofthose SAP's measured in both 1-layer and 6-layer AAP tests decreased, asexpected, with increasing CRC [FIG. 19]. SAP EFF decreased withincreasing CRC because polymers with high CRC have low gel strength andthis leads to the well-known phenomenon of gel blocking under pressure.Further, SAP EFF for the folded 6-layer cores of the present inventionwas higher than the SAP EFF of a 1-layer core for values of CRC greaterthan about 30 g/g. The 0.7 SAP AAP of many SAP's in 1-layer and 6-layercores are shown in FIG. 20. Overall, 0.7 SAP AAP decreased withincreasing CRC, but it was possible to identify SAP's that provided ahigh value of 0.7 SAP AAP (i.e. 28 g/g) at a relatively high value ofCRC (i.e. 36 g/g). Comparing SAP's with CRC values of 30 and 36 g/g, itcan be seen that it was possible to identify SAP's with a CRC of 36 g/gthat provided a 20% increase in CRC with only a 3% decrease in 0.7 SAPAAP. For this reason, SAP's with a high 0.7 SAP AAP and a CRC in themid-range of 33-38 g/g are preferred for use in a folded, multi-layercore. Other measurements of the liquid-holding capacity of SAP's in amulti-layer cores, CAP and RUL, were found to be mostly independent ofCRC over a wide range of CRC [FIGS. 21 and 22].

2. SAP Asymmetry

Examples of SAP asymmetry are shown in FIGS. 23 and 24. SAP asymmetry isthe ratio of the weight of the heavier tissue layer and its attached SAPto the weight of the lighter tissue layer and its attached SAP after thelayers are gently separated after warming in an oven at about 50° C. for10 min. FIG. 23 shows SAP asymmetry for nine samples cut from a laminate533 mm in width. Three of the samples were equally spaced over thecross-direction (CD) of the material and this was repeated at threeequally spaced positions in the machine-direction (MD), in a 3×3 matrix.The 533 mm width of material was one-half of the width of parentmaterial at 1066 mm width, thus in FIG. 23, TS indicates the edge of theweb and S indicates the center of the web as made on the machine.Samples 1, 2, and 3 were samples cut in the machine-direction at aparticular position in the cross-direction. FIG. 23 shows that thislaminate was made with relatively low values of SAP asymmetry (i.e.,less than a value of 4). There were statistically significantdifferences in SAP asymmetry in the MD and CD directions. FIG. 24 showsa preferred level of SAP asymmetry for the laminate. Values of SAPasymmetry are all greater than 4 and there are no statisticallysignificant differences in CD and MD directions. Process settings thatdrive SAP asymmetry can be specific to the web path and geometry of anyparticular process used to make the laminate and these settings may needto be optimized using standard optimization techniques and designedexperiments.

B. Multi-Layer Folded Core Experiments

1. One-Part and Two-Part Multi-Layer Cores Generally

Rapid liquid acquisition over multiple doses, full-length coreutilization, minimization of side leakage, and high SAP efficiency areexhibited by One-Part cores comprised of a folded, multi-layer laminate.These attributes are also exhibited by Two-Part cores, where at leastone of the parts of the core is comprised of a folded, multi-layerlaminate. Two-Part cores provide an effective means to zone absorbentcapacity and reduce raw material cost while maintaining key attributesof the folded, multi-layer laminate. The folded multi-layer laminate canbe placed in an absorbent article with the open side of the channelfacing the wearer or with the open side facing the backsheet of theabsorbent article. The latter is possible because a single layer oflaminate in the center of a folded, multi-layer core has sufficientpermeability to function as an open channel.

2. Rapid Liquid Acquisition for Multiple Doses

A conventional liquid acquisition and rewet test was performed accordingto the following procedure. The liquid acquisition is the time inseconds for a section of core to absorb a known volume (usually 75 or100 ml) of 0.9% saline through a 48 mm diameter dosing head. Productswere equilibrated overnight and tested in a room maintained at 22° C.and 50% RH. The saline solution was used at a room temperature of 22° C.The dosing head was weighted and had a screen on one end to apply aneven pressure of 0.5 psi to the core at the point of liquid dosing. Theremainder of the core was restrained under a 150 mm×300 mm plate thatweighed 600 g. The dosing head extended through a hole drilled throughthe core restraining plate and was positioned over the center of theacquisition layer used on the absorbent core. A 75 ml dose was meteredto the dosing head at a rate of approximately 20 ml/sec and the time toabsorb the liquid was recorded as the acquisition time (±0.1 sec). After30 minutes of equilibration, the restraining plate was removed, and astack of ten filter papers (Whatman 4, 70 mm) were placed on the dosingarea under a cylindrical brass weight of 60 mm diameter. The weightapplied a pressure of 0.8 psi. After two minutes the weight was removedand rewet was determined from a difference in weight between the wet anddry filter papers (±0.01 g.). The acquisition and rewet test wasrepeated for 4 doses.

Compared to conventional cores, folded cores show improved acquisitiontimes (i.e., the time to absorb a dose of liquid) and rewet afteradditional doses of liquids and exudates. In conventional cores, theacquisition time tends to rise with each subsequent dose, i.e., thesecond dose takes longer to absorb than the first dose, the third dosetakes longer to absorb than the second dose, and so on. In contrast, theacquisition time for multi-layer absorbent cores according to thepresent invention falls abruptly after the first dose and stays at a low(good) value for the second, third, and fourth doses.

Liquid acquisition and rewet performance are shown in FIGS. 25A and 25Bfor a diaper prototype containing a One-Part, 6-layer, folded,multilayer core comprised of a 45 gsm laminate with only 8.9 g. of SAP.Despite the low SAP basis weight, the multi-layer core performed betterin lab tests than a premium private label fluff/SAP core containing 9.5g. of fluff and 11.5 g. of SAP (“Control 1”), and a market-leading“fluffless” diaper containing acquisition fiber and more than 12 g. ofSAP (“Control 2”). FIG. 25A shows the characteristic improvement inacquisition time for the folded multilayer core (i.e., 6-45 W211) afterthe first liquid dose. The fourth dose acquisition time for the foldedmultilayer core is only 10 sec., compared to remarkably poorer values of30 sec. for Control 1 and 24 sec. for Control 2. These results arestatistically significant at 95% confidence. Fourth dose rewet of thefolded multilayer core, shown in FIG. 25B, is better than that of thepremium conventional fluff/SAP core and comparable to that of Control 2.Absorbent cores with less than 0.5 g. of rewet are generally “dry” tothe touch.

In addition, to illustrate the advantages of the folded, multi-layercore design, the liquid acquisition and rewet performance of a 6-layercore containing a central channel was compared to a 6-layer core withouta central channel FIGS. 26A and 26B. FIG. 26A shows the acquisitiontimes for a One-Part, 6-layer, folded core (100 mm width) comprised of alaminate made with 60 gsm of S125D SAP and an unfolded core (i.e., NOFOLD) comprised of six stacked (i.e., unfolded) layers of the samelaminate. The data on the right side of FIG. 26A show that acquisitiontimes for a core constructed with unfolded layers of the laminatewithout a central channel increase with each dose, as the acquisitiontimes do for conventional fluff/SAP cores. Furthermore, as shown in FIG.26B, rewet for the folded core with a central channel is better thanthat of core made with the unfolded layers of laminate. This illustratesthe advantages of the folded core and a central channel geometry withthe laminates of the present invention. A 6-layer core without a centralchannel has no mechanism for containing large volumes of liquid anddirecting the bulk flow of liquid both longitudinally along the core andlaterally within the crenellation. As FIG. 26A shows, liquid acquisitiontime for the 6-layer folded core decreased from 19 seconds to 11 secondsover four 75 ml doses, whereas acquisition for the unfolded coreincreased from 29 sec to 48 seconds over the four doses. Similarly, asshown in FIG. 26B, the folded core exhibits low rewet over the multipledoses, compared to the unfolded core, which exhibits significantlyincreased rewet after the fourth dose.

According to additional testing, a liquid acquisition and rewet test wasperformed on a conventional fluff/SAP absorbent core and on variousembodiments of Two-Part absorbent cores according to the presentinvention. More specifically, each Two-Part core sample comprised afolded, multi-layer surge core with either four or six laminate layersand an unfolded base core. The various multi-layer cores comprisedvarying basis weights and SAP types, according to the table below. Asfor nomenclature of Samples 2-9, the leading digit signifies the numberof layers, the next two digits, such as “60” and “89,” signify the SAPgsm and the remaining information, such as “S125D” and “W211” signifiesSAP type.

Surge Core Unfolded Base Core (80 mm × 215 mm) (80 mm × 345 mm) UnfoldedUnfolded Laminate Laminate Basis Weight Basis Weight NO. Layers (gsm)SAP type (gsm) SAP Type 1. Conventional 558 Fluff/SAP (“Control”) 2. 660 T9030 60 T9030 3. 4 89 T9030 89 T9030 4. 6 60 W112A 60 W112A 5. 4 89W112A 89 W112A 6. 6 60 S125D 60 S125D 7. 4 89 S125D 89 S125D 8. 6 60W211 60 W211 9. 4 89 W211 89 W211

The surprising and unique results are described below and illustrated inFIGS. 27A-27B. Results in FIGS. 27A and 27B were obtained using Two-Partcores comprised of a partial 215 mm length upper layer of 4- and 6-layerfolded cores containing 60 and 89 gsm of four different superabsorbentpolymers. The lower layer of the Two-Part cores was comprised of asingle layer (345 mm length) of a laminate of the type used to make theupper core. Both upper and lower layers had a folded width of 80 mm.Compared to a conventional fluff/SAP core containing 9.5 g. of fluff and11.5 g. of SAP (i.e., Control), the best overall liquid acquisition andrewet performance were obtained for the core that contained an uppercore made with 6 folded layers of a laminate containing 60 gsm of S125DSAP (i.e., 6-60 S125D).

As shown in FIG. 27A, for each folded core (samples 2-9) the second dosehad a markedly improved (i.e., lower) acquisition time over theacquisition time of the first dose. For most of the folded cores, theacquisition times continued to improve for the third dose (cores 2, 3,4, 5, 6, 7, and 8). For some of the folded cores, the acquisition timesimproved even for the fourth dose (cores 2, 3, 4, and 6). The rewetresults were better than for conventional fluff/SAP cores and nearlycomparable to the best-in-class fluffless cores.

In contrast, the results for the control sample, a conventional premiumpulp/SAP absorbent article comprising 9.5 g. fluff and 11.5 g. SAP, andreferred to in FIGS. 27A-27B as “Control,” reveal that the acquisitiontime fell very slightly for the second dose, then rose significantly forthe third and fourth doses. For the fourth dose of 75 ml, theacquisition times of the folded multi-layer cores were about one-halfthat of the conventional fluff/SAP core. Further, the results of FIG.27B show that the novel Two-Part multi-layer folded cores exhibit rewetproperties comparable to conventional absorbent articles.

Thus, FIGS. 27A-27B clearly show an advantage for Two-Part cores over aconventional fluff/SAP core in that the inventive Two-Part coresexhibited improved acquisition and faster liquid acquisition for apreferred SAP that had a mid-range permeability and CRC value (i.e., aCRC in the range of 33-38 g/g) as described earlier for optimization ofa 6-layer laminate structure. Tests of SAP 0.7 AAP for a 6-layerlaminate, discussed in an earlier section, have been used to identifypreferred SAP properties for making laminates for a folded, multi-layercore. Particularly, these results were even more pronounced for surgecores comprising 6-layers of absorbent laminate at 60 gsm SAP comparedto those comprising 4-layers at 89 gsm. The SAP basis weight of thelaminates was adjusted to provide approximately the same amount of SAPin the 6-layer and 4-layer folded cores.

3. Core Utilization

Improved liquid acquisition and rewet performance discussed above forOne-Part cores can be understood in terms of improved core utilizationof the folded core design over a conventional design. This is shown inFIG. 28, the top half of which reflects liquid spreading for aconventional fluff/SAP core, and the bottom half of which reflectsliquid spreading in a multi-layer core according to the presentinvention. After four liquid doses of 75 ml of a 0.9% saline solution,cores were cut into five equal sections (i.e., from front to back) andweighed to determine the amount of liquid in each section. FIG. 28demonstrates that liquid spreading was greater in the folded multilayercore. Absorbent material at the ends of the multilayer core was moreeffectively utilized (evidenced by the more even absorption across thesections) and the amount of liquid in the center of the core relative tothe conventional control design was reduced. As FIG. 28 reflects, morethan 100 grams of liquid were present in each of Sections 2 and 3 of thefluff/SAP core as a result of limited radial liquid spreading. Incontrast, less than 70 grams of liquid were present in each section ofthe folded multilayer core as a result of liquid spreading by thecentral channel and crenellations of the core. The control core withexcessive liquid in the center or crotch area of the core exhibitedabout 25 g. of side leakage after the fourth dose. The folded multilayercore exhibited no side leakage in the liquid acquisition and rewet test.Methodology for the measurement of side leakage is described in the nextsection.

The rate of absorbency of the SAP used in the laminate can be selectedto further facilitate effective core utilization. A SAP with an optimalrate of saline absorption will spread evenly in a folded, multi-layercore, providing better core utilization and a lower probability ofpremature leakage in mannequin testing. It is generally understood thatoverly rapid absorption of liquid by SAP at the point of dosing shouldbe avoided. If this occurs, the core quickly becomes saturated at thedosing point and bulk liquid spreading on the surface of the coreincreases the probability of leakage. The effect of SAP absorption rateon mannequin leakage performance will be discussed in a later section.

4. Minimal Side Leakage

A side leakage test was performed in conjunction with the liquidAcquisition and rewet testing for the One-Part and Two-Part cores shownin FIGS. 25A-25B and 27A-27B, respectively. Side leakage can occur byliquid running off of the surface of the core, as well as by movingthrough the core itself and leaking from the side. In this test, anabsorbent bed pad was cut to a width that was 50 mm wider (i.e., 25 mmon each side) than the core and placed under the core samples. At theend of the testing, the bed pad material was re-weighed to determine theamount of side leakage that occurred during the testing. Test resultsrevealed no measurable weight gain in the bedpad, for any of theOne-Part and Two-Part cores, thus indicating that the cores did notexperience any side leakage. In comparison, conventional fluff/SAP coreshad 18-36 g. of side leakage of test liquid after the fourth dose of 75ml (300 mls total) in this test.

5. Width of Central Channel

It has been discovered, according to the present invention, that thecross-directional width of the central channel should be greater than 2mm for good liquid acquisition and rewet performance. FIG. 29A showsliquid acquisition times for 6-layer folded cores that had centralchannel widths of 2 mm, 10 mm, and 25 mm. These were One-Part cores of100 mm width that were comprised of a laminate containing 60 gsm ofS125D SAP. The core that had a central channel width of 2 mm did notexhibit good liquid acquisition performance when compared to the widerchannel cores. As discussed above, a 2 mm channel does not providesufficient free volume for liquid acquisition and can close shut as thecore swells with absorbed liquid. The channel width of 10 mm exhibitedsatisfactory results, but care must be taken that the effective channelwidth is not decreased because of buckling of the thin section of thecore between the folded side areas of the core under conditions ofactual use. For this reason, a channel width greater than 15 mm ispreferred. The data in FIG. 29A shows a modest reduction (i.e.,improvement) in liquid acquisition times for a 25 mm channel relative tothat for a 10 mm channel. Improvements in rewet are also observed forcores with central channel widths of 10 mm and 25 mm, compared to onewith a central channel width of only 2 mm (FIG. 29B).

It is also possible to adjust the second and third folds of a laminateto make a folded core that has a central channel that is wider at thetop and narrower in the interior of the core. Examples of this foldinggeometry are illustrated in FIGS. 2, 8 and 16. In FIG. 8, the foldedcore has a terraced central channel comprised of separate layers oflaminate. The separate layers can be secured to one another via adhesiveor mechanical bonding along the base of the core. In this embodiment,the separate layers of laminate encapsulate an optional acquisitionmaterial in the interior of the core. The acquisition material can becomprised of TAB polypropylene or polyester fiber, synthetic fiber tow,low-twist sliver or yarn staple fiber, or cellulosic acquisition fiber.

C. Mannequin Testing of Baby Diapers Containing Folded Multi-Layer Cores

For the mannequin testing, Large Size 4 diapers were constructed toinclude absorbent cores according to the present invention. Thesediapers were tested on a Size 4 prone Courtray mannequin diaper testercommercially available from SGS Courtray EURL, Douai, France, using theCourtray absorption before leakage (ABL) protocol provided with theapparatus.

The mannequin is made of a soft silicone rubber and has appropriatedimensions for a Large Size 4 infant. In this test a diaper was fittedto the mannequin and stressed until leakage with multiple doses of 0.9%saline test liquid supplied by Lab Chem Inc., Cat. No. 07933, which hada specification of 0.9% Wt./Vol.±0.005% sodium chloride. Products wereequilibrated overnight and tested in a room maintained at 22° C. and 50%relative humidity. The saline solution used was at a room temperature of22° C. Absorption Before Leakage (ABL) was defined as the mass of liquidthat the diaper absorbed (±0.01 g.) under conditions of the test beforea leak occurred. Higher values of ABL=(Final Weight of Diaper afterLeakage)−(Initial Dry Weight of Diaper) are preferred. The mannequin wasprovided with female and male dosing tubes. The male mode was used inall tests. The liquid was pumped to the mannequin at a rate of 7 ml/secusing a Masterflex L/S Digital Drive, Model No. HV-07523-80 and aMasterflex L/S Easy-Load II Pump Head, Model No. EW-77200-62. Themannequin was placed on a rectangular foam pad that had a waterproofcover. Leakage was detected visually on a sheet of tissue placed underthe mannequin. Times were measured using a stopwatch±1 sec.

General instructions for fitting a diaper on the mannequin follow. Thediaper should be folded in the longitudinal direction forming a pouch,concave inward, between the legs of the mannequin. The standing gathersof the product need to come to rise while applying it to the mannequin,paying close attention to how they lie in the groin. Correct position isachieved when the standing gathers remain extended and surround the maleadapter evenly. The outer leg elastics are folded outwardly in thecrotch region so that the inner face of the product remains in contactwith the skin of the mannequin. The tabs of the diaper are unfolded andput on smoothly. The diaper is spread flatly on front and backside toensure an even fit. The diaper is then fixed in place with the tapetabs. The tabs should be centered on the landing zone. On a Size 4 Largediaper the ends of the tabs should nearly touch (1 mm±0.5 mm) in themiddle of the landing zone. The front and back ends of the diaper shouldremain at equal height on the torso of the mannequin. Small adjustmentscan be made to align the front and back ends of the diaper, ifnecessary. Differences in diaper dimensions can affect the tightness offit of the diaper around the waist of the mannequin. In the testingdescribed below, folded multi-layer cores were tested incommercially-available diaper chassis.

The protocol for liquid dosing of the product is given in the tablebelow. An initial dose of 75 ml of liquid was delivered at t=0 with themannequin lying on its belly. At t=4 min. the mannequin was turned onits back. At t=5 min. a dose of 25 ml was delivered with the mannequinlying on its back. At t=9 min. the mannequin was turned onto its belly,rotating the torso in the same direction as turned initially. At t=10min. a dose of 75 ml was delivered with the mannequin lying on itsbelly. The mannequin remained on its belly for the remainder of the testand was dosed with 25 ml every 2 min. (e.g., t=12, 14, 16 min., etc.)until leakage occurred. Saline solution that leaks out of the diaperwill be absorbed and spread by the tissue layer that covers the pad andwill present a visible dark spot. After a leak occurred, the diaper wasremoved and weighed. The difference between the wet and initial dryweights of the diaper was defined as Absorption Before Leakage (ABL).

Time (min) Position Dose No. Dose Vol. (ml) 0 Belly 1 75 4 Back — — 5Back 2 25 9 Belly — — 10 Belly 3 75 After 10 min. the mannequin remainson its belly and is dosed with 25 ml every 2 min. until a leak occurs.

The diaper chassis used for making diapers containing the folded,multi-layer cores was a commercially available, private label disposablediaper. Diapers for mannequin testing were created using the followingprocedure. A 533 mm wide laminate was folded into a multi-layer core(e.g., a 115 mm wide, 5-layer core with a 10 mm wide channel asillustrated in FIG. 10A), and then cut to length (e.g., 300 mm). Thediaper was taped flat to a table-top, liner side down, using tapeattached to the corners of the diaper as needed keeping the elasticsextended. A slit was cut through the centerline of the back sheet alongthe length of the diaper core. The core was removed through this slitalong with any residual fluff adhered to the envelope and the folded,multi-layer core was inserted into the diaper in place of the removedconventional core. The slit in the diaper was neatly closed with tapewith sufficient overlap to effectively seal the slit. The diapers wereplaced on the Courtray mannequin and the ABL was measured and recordedper the procedure supplied by the manufacturer of the mannequin.

1. One-Part and Two-Part Multi-Layer Cores

Folded, multi-layer cores were made with laminates containing S125D andW211 SAP's and compared to commercially available baby diapers in amannequin leakage test. ABL values measured in these tests are given inthe table below.

Absorbency Before Leakage or ABL BABY DIAPER CORE (mean g., n = 4 ± 95%Size 4, Large confidence interval) Private label fluff/SAP core 206 ± 19Branded, pulpless core No. 1 184 ± 33 Branded, pulpless core No. 2 259 ±39 One-Part Folded 6-layer Core 179 ± 2 (345 mm × 110 mm) Laminate with45 gsm W211 SAP ADL = 40 gsm TAB (110 mm × 149 mm) One-Part Folded6-layer Core 263 ± 17 (345 mm × 110 mm) Laminate with 89 gsm S125D SAPADL = 40 gsm TAB (110 mm × 149 mm) One-Part Folded 6-layer Core 195 ± 9(345 mm × 110 mm) Tri-tissue laminate with 45 gsm W211 SAP ADL = 40 gsmTAB (110 mm × 149 mm) Two-Part Folded Core 209 ± 12 Upper Part: 6-layer,60 gsm S125D SAP, 215 mm × 100 mm Lower Part: 1-layer, 89 gsm W211 SAP,345 mm × 100 mm ADL = 60 gsm TAB (100 mm × 149 mm)

As the table reflects, One-Part folded, multi-layer cores made with alaminate containing only 45 gsm of SAP (i.e., 8.0 g. of SAP per core)provided adequate mannequin leakage performance at much reduced rawmaterial usage. In comparison, the private label, fluff/SAP coreprovided similar ABL but contained significantly more (11.5 g.) of SAP.As the table further reflects, One-Part cores with 15.8 g. of SAP (89gsm of SAP in laminate) and Two-Part cores with 9.7 g. of SAP performedas well or better than the private label, fluff/SAP core and, in thecase of the One-Part core, equal to the better performing branded,pulpless core.

2. Width of Central Channel

Additionally, and as mentioned previously, it has been found that it isimportant to maintain a central channel width in the folded core greaterthan about 2, and preferably at least about 10, mm for optimum mannequinABL performance and for liquid acquisition. More preferably, the centralchannel width should be in the range of about 15 to about 20 mm. Asmentioned, channels of these preferred widths compensate for theoccasional formation of a “ruck” or overlap in the center of the core atthe base of the channel due in part to pressure applied to the sides ofthe core by the wearer and for swelling of the SAP in the laminateduring liquid absorption, which further reduces the width of the channeland reduces performance. The following table records average mannequinABL values for 5-layer cores made with 100 gsm W125 SAP in the laminatemade with the different channel widths indicated. As shown, the ABLresults improved with increased channel width.

ABL Channel Width (mm) (g) 2-4 mm 215 5-7 mm 237 8-10 mm  282 PooledStd. Dev. = 8 g

3. Rate of Liquid Absorption of SAP and SAP Asymmetry of Laminate

SAP with an optimal rate of liquid absorption and high levels of SAPasymmetry were shown to improve mannequin ABL performance. First, themannequin tests confirmed that a core of the present invention using SAPwith a moderate absorbency time performed better than one having ashorter absorbency time. Specifically, in the mannequin tests, SAP witha 0.9% saline absorbency time in the range of about 160 sec. to about220 sec. provided improved mannequin ABL compared to a comparable coremade with a SAP with an absorbency time that was less than about 160sec. FIG. 30 reports these measurements of the time of liquidabsorption. FIG. 30 shows that the time of absorption of two differentlots of S125D SAP was greater than that of superabsorbent polymers W211and W125, and that these were statistically significant differences.S125D SAP was found to provide better mannequin leakage performance thanW125 in one-part MLC cores when the laminates were made with comparableSAP asymmetry (see table below). All of the cores in the table belowwere constructed with a core length and width of 345 mm×110 mm and anADL of 40 gsm TAB nonwoven (149 mm×110 mm) supplied by PGI Polymer GroupInc., Charlotte, N.C. Cores were placed into diapers as described aboveand tested for mannequin leakage.

RATE OF ABSORBENCY SAP CORE OF SAP (sec.) ASYMMETRY ABL (g) One-PartFolded 6- 141 1.5:1 169 ± 10 layer Core to Laminate with 89 gsm 3.5:1W125 SAP One-Part Folded 6- 203 1.5:1 246 ± 14 layer Core to Laminatewith 89 gsm 4.0:1 S125D SAP One-Part Folded 6- 141 4.5:1 259 ± 13 layerCore to Laminate with 89 gsm 6.5:1 W125 SAP

SAP absorbency time was measured by placing 0.5 g. (±0.01 g.) of a SAPin a 50 mm diameter disposable aluminum weigh pan, and pouring 15 ml ofa 0.9% saline solution over the polymer at a rate of about 5 ml/sec.Temperature of the SAP and saline solution was 22° C. A stopwatch wasstarted during the pouring of the saline solution. After pouring thesaline solution into the pan containing the SAP, the pan was swirledgently to provide an even distribution of SAP on the bottom of the pan.When all free liquid on the top of the SAP had been absorbed, a channelwas formed in the SAP. Initially water filled the channel, but afterrepeating this process every two seconds, a point was reached wherethere was no free liquid on the bottom of the pan to fill the channel.At this point the stopwatch was stopped and the absorption time wasrecorded. With regard to asymmetry, all three laminates in the tableabove were prepared with 89 gsm of SAP, two plies of 17 gsm 3995 tissueas substrates, and 3.2 gsm SP 507 adhesive. Tests were performed tomeasure SAP asymmetry. The first two laminates in the table aboveexhibited SAP asymmetry values that averaged well below 4:1 over most ofthe surface of the sheet. SAP asymmetry values for the second sampleabove are shown in FIG. 23. The third laminate (FIG. 24) was producedwith similar SAP content but with SAP asymmetry values well over 4:1over most of the laminate.

In considering these results, it should be noted that W125 and S125DSAP's exhibited comparable values of CRC and AAP, but different liquidabsorption times. Mannequin absorption before leakage (ABL) for thediapers made with the low asymmetry laminate and the SAP with theshorter absorption time averaged 169±10 g.; n=3. ABL for the diapersmade with low asymmetry laminate and the SAP with the longer absorptiontime of 203 sec. averaged 246±4 g.; n=6. Mannequin leakage performancewas better for the core that contained the SAP with the longerabsorption time. Without being restricted to any particular theory, itis thought that slower absorbing SAP facilitates more even spreading ofliquid in the core, and helps to prevent oversaturation of the core atthe dosing point. This oversaturation can inhibit penetration of liquidinto the core and allow free liquid to leak from the absorbent product.

Second, turning to SAP asymmetry, it can be shown that a foldedmulti-layer core made using a laminate that had a value of SAP asymmetrygreater than 4 performed better in a mannequin leakage test than a coremade using a laminate with a lower value of SAP asymmetry. The mannequinabsorption before leakage (ABL) for the diapers made with the lowasymmetry laminate and the SAP with the shorter absorption time averaged169±10 g.; n=3. ABL for the diapers made with the high asymmetrylaminate and the same SAP with the shorter absorption time averaged259±13 g.; n=6. This test showed that an increase in SAP asymmetry ofthe laminate can improve the mannequin leakage performance of a folded,multi-layer core. This improvement was achieved using a SAP in thelaminate that had a liquid absorption rate that was somewhat too low foroptimal performance. Laminates made with both the preferred,slower-absorbing S125D SAP and higher SAP asymmetry generated ABL valuesthat were in the range of 240-270 g, i.e., not significantly higher thanthe values obtained using either the preferred SAP with the longer timeof liquid absorption or the laminate with the higher SAP asymmetryalone.

4. Orientation of Laminate in Absorbent Product

Mannequin testing also revealed that, for absorbent articles made withcores of the present invention constructed from laminate materialexhibiting significant SAP asymmetry, improved mannequin ABL occurredwhen the cores were constructed with the side with less SAP bonded to itpresented towards the outer surface of the folded core.

5. ADL Width and Diaper Chassis Construction

As part of the mannequin testing, experiments were performed to analyzevarious additional chassis features of absorbent articles comprisingmultiple folded cores according to the present invention. Specifically,in preparation for the mannequin diaper trial, certain Designs ofExperiments (“DOE”) were done to determine the preferred dimensions forseveral of these chassis features in order to yield the best mannequinperformance. These experiments were 4-factor, 2-level DOE's performedwith One-Part cores unless indicated otherwise. The results from theseDOE's are presented in FIGS. 31 A-C. Specifically, main effects plotsfor DOE #1 are shown in FIG. 31A. Results indicated better mean valuesof ABL for: (a) TAB fiber filled vs. unfilled central channel; (b) 110mm ADL width vs. 65 mm ADL width; (c) Two-Part core vs. One-Part Core;and, (d) 30 min. time between doses vs. 2 min. time between doses. The30 min. time between doses was a departure from the standard testprotocol. Main effects plots for DOE #2 are shown in FIG. 31B. Resultsindicated better mean values of ABL for: (a) 215 mm ADL length vs. 103mm ADL length; (b) 110 mm ADL width vs. 65 mm ADL width; (c) 25 mm ADLoffset vs. 0 mm offset; and, (d) 0 mm tackdown position vs. 75 mmtackdown position. Main effects plots for DOE #3 are shown in FIG. 31C.Results indicated better mean values of ABL for: (a) no differencebetween ADL lengths of 149 and 215 mm when ADL width was 110 mm; (b) 50mm ADL offset vs. 25 mm offset; (c) 0 mm tackdown position vs. 25 mmtackdown position; and, (d) no difference between SAP basis weights (BW)of 45 and 60 gsm.

A preferred diaper design having a number of these features included afive-layer folded core as illustrated in FIG. 10A. The design had a corewidth of 115 mm, positioned with the leading edge of the folded coreabout 2 mm from the leading edge of the front tape and about 26 mm fromthe front edge of the diaper. The ADL was a high-loft Through-Air-Bonded(TAB) nonwoven ADL having a basis weight of 40 gsm and length of 149 mmand a width of about 110 mm with the leading edge of the ADL positionedabout 50 mm from the front edge of the core. FIG. 15 presents contourplots generated from designed experiments predicted that mannequinleakage performance would be independent of ADL length (over a rangefrom about 149 mm to about 183 mm) when ADL widths were greater thanabout 105 mm, or 91% of the absorbent core width. FIG. 15 also showsthat mannequin leakage performance improves with ADL length when the ADLwidth was less than about 100 mm.

It also was found that the standing leg gather should extend to thefront of the core with the tack down at this location (i.e., a tackdownposition of 0 mm). It further was found that a zone treated top sheetshould have a treated hydrophilic zone of a width of about 108 mm. Also,adjustment of the ADL width to nearly equal the width of the core, andthe other chassis adjustments mentioned above, were important forachieving the highest levels of mannequin leakage performance of a babydiaper containing a folded, multi-layer core. The ADL in many absorbentproducts, such as diapers and AI absorbent products, is frequentlynarrower than the core. The practice of making the ADL as wide as thecore for optimum performance for the core of the present invention is adeparture from this practice.

The table below shows the magnitude of the difference in mannequinleakage performance that was measured for optimized and non-optimizedbaby diapers according to the factors described above. Channel widthremained the same at 10 mm. Both diapers were made with One-Part,folded, 6-layer cores made with a laminate comprised of 89 gsm of S125DSAP.

Standing Gather Core Position ADL Offset Tackdown (mm Folded Core ADLDimensions (mm from (mm from from front ABL Core Width (mm) (l × w)front of diaper) front of core) of core) (g.) ADL and 100 197 mm × 65mm  50 25 50 157 ± 5  Chassis Not Optimized ADL and 110 149 mm × 110 mm26 50 0 246 ± 14 Chassis Optimized

It is believed that optimal performance of larger absorbent articles,such as Adult briefs and pull up underwear, and smaller absorbentarticles, such as Adult bladder control pads, can be achieved withfolded, multi-layer cores by making appropriate changes in chassisdesign, adjusted for core size.

6. Acquisition Fiber

The mannequin testing results further showed that cellulosic acquisitionfiber provided better mannequin ABL performance than TAB nonwoven ADLwhen used with the folded, multi-layer core of the present invention.Two commercially available diaper products were selected as “controls”for the experiment. The first diaper was a branded diaper product havinga pulpless core and the second diaper was a private label diaper havinga pulp/SAP core. The core and the ADL of the private label product wereremoved and the diaper was reconstructed to include the core and ADL ofthe branded product. Thus, the two commercially available productsdiffered only by diaper chassis. As can be seen from the followingtable, the branded product exhibited better ABL than the reconstructedprivate label product. A third control was prepared using the privatelabel chassis and a TAB ADL and a cellulosic fiber/SAP core. Thiscontrol exhibited ABL inferior to Samples 1 and 2.

Multi-layer core products were constructed to compare to the threecontrols. Specifically, folded, multi-layer cores were made withlaminates containing 45 gsm W211 SAP and 89 gsm S125D SAP and includedin the private label chassis. The ABL performance of prototypes madewith both the 45 gsm and 89 gsm SAP laminates was improved when a 40 gsmTAB ADL on those cores was replaced with an ADL comprised of about 230gsm of acquisition fiber and a TAB layer of nonwoven. The folded,6-layer core made with the 89 gsm S125D SAP and the cellulosicacquisition fiber provided an ABL value of 351±40 g., compared to avalue of 259±39 g. for Sample 1. At n=3, this improvement in mannequinleakage performance for the folded, multi-layer core was statisticallysignificant at 95% confidence.

SAMPLE CHASSIS ADL CORE ABL (g.) 1 Branded diaper Acquisition FiberBranded, pulpless core 259 ± 39 chassis and TAB 2 Private labelAcquisition Fiber Branded, pulpless core 229 ± 33 diaper chassis and TAB3 Private label 60 gsm TAB (197 mm × Fluff (x g.)/SAP (11.5 g.) 206 ± 19diaper chassis 65 mm) 4 Private label 40 gsm TAB (149 mm × One-PartFolded 6-Layer 179 ± 2 chassis 110 mm) with 45 gsm W211 SAP in Laminate5 Private label Acquisition Fiber One-Part Folded 6-Layer with 225 ± 30chassis and TAB 45 gsm W211 SAP in Laminate 6 Private label 40 gsm TAB(149 mm × One-Part Folded 6-Layer 263 ± 17 chassis 110 mm) with 89 gsmS125D SAP in Laminate 7 Private label Acquisition Fiber One-Part Folded6-Layer with 351 ± 40 chassis and TAB 89 gsm S125D SAP in Laminate

D. Core Stability Testing

A laboratory core stability test was developed to provide a measure ofthe integrity and durability of the core and to simulate its performancein actual use. Fluff/SAP cores can fracture in use and lead to prematureleakage. In the Core Stability test a diaper sample was prepared byremoving all leg and leg gather elastics along with all side panels. Theabsorbent core was dosed with 50 ml of a dyed 0.9% saline solution at apoint 50 mm forward of the product centerline in the machine direction.After 15 minutes, the product was clamped onto a horizontal supportingrod to hang vertically by the forward end of the article from a singlecentrally located clamp. The supporting rod and attached product wasdropped from a height of 40 mm repeatedly onto hard stops until theabsorbent core in the product fractured. The number of drops required tofracture the core was recorded as Core Stability. Four products weretested to obtain a mean value of core stability.

Four commercially available diapers, two branded and two private label,with conventional fluff/SAP absorbent, non-folded cores were selectedfor the test, along with a One-Part folded, 5-layer core constructedwith a laminate containing 97 gsm of SAP. The folded, multi-layer corewas produced in a machine-made diaper using a chassis that wascomparable to the chassis of one of the private label chassis. All ofthe diapers with the fluff/SAP cores had a value of core stability inthe range of 10 to 33 drops. The folded, multi-layer core was dropped250 times without any evidence of core fracture. Actual values of meannumber of drops and 95% confidence interval of the mean are shown in thetable below.

CORE STABILITY (No. of Drops DIAPER CHASSIS ABSORBENT CORE from 40 mm)Private label chassis No. 1 One-Part Folded, 5- >250 Layer 97 gsm SAPLaminate Private label chassis No. 1 Fluff/SAP 33 ± 8 Private labelchassis No. 2 Fluff/SAP 22 ± 7 Branded chassis No. 1 Fluff/SAP 16 ± 7Branded chassis No. 2 Fluff/SAP 11 ± 5

The above specification and examples provide a complete description ofthe structure and use of exemplary embodiments. Although certainembodiments have been described above with a certain degree ofparticularity, or with reference to one or more individual embodiments,those skilled in the art could make numerous alterations to thedisclosed embodiments without departing from the scope of thisinvention. As such, the various illustrative embodiments of the presentstructures and methods are not intended to be limited to the particularforms disclosed. Rather, they include all modifications and alternativesfalling within the scope of the claims, and embodiments other than theones shown or described may include some or all of the features of thedepicted or described embodiments. For example, components may becombined as a unitary structure and/or connections may be substituted.Further, where appropriate, aspects of any of the examples describedabove may be combined with aspects of any of the other examples depictedor described to form further examples having comparable or differentproperties and addressing the same or different problems. Similarly, itwill be understood that the benefits and advantages described above mayrelate to one embodiment or may relate to several embodiments.

The claims are not to be interpreted as including means-plus- orstep-plus-function limitations, unless such a limitation is explicitlyrecited in a given claim using the phrase(s) “means for” or “step for,”respectively.

The invention claimed is:
 1. An absorbent core comprising alongitudinally folded absorbent laminate, the longitudinally foldedabsorbent laminate comprising: an upper laminate layer; a lower laminatelayer; and an absorbent layer positioned between the upper laminatelayer and the lower laminate layer, the absorbent layer comprisinggreater than about 90 percent by weight super absorbent polymer (SAP);wherein the longitudinally folded absorbent laminate is folded to form alongitudinally folded multi-layer absorbent laminate of at least fivelayers of laminate; wherein the longitudinally folded multi-layerabsorbent laminate has two lateral laminate sides and a width extendingbetween the laminate sides, a first one of the layers spans the entiretyof the width, a second one of the layers is disposed above the firstlayer and spans between 80 percent and 92 percent of the width, thirdand fourth layers are disposed between the first and second layers andeach span less of the width than does the second layer, and a fifthlayer is disposed between the third and fourth layers and spans less ofthe width than does at least one of the third and fourth layers; andwherein laterally opposing portions of at least the second and thirdlayers define a longitudinally-extending channel above at least thefirst layer.
 2. The absorbent core of claim 1, further comprising athird laminate layer between the upper laminate layer and the lowerlaminate layer.
 3. The absorbent core of claim 1, wherein the channelwidth is at least about 8 mm wide.
 4. The absorbent core of claim 1,further comprising a channel insert disposed in the channel, the channelinsert configured to improve liquid acquisition and reduce leakage ofliquid from longitudinal ends of the channel.
 5. The absorbent core ofclaim 1, where at least one of the upper laminate layer and the lowerlaminate layer comprises tissue.
 6. The absorbent core of claim 1,wherein the longitudinally folded absorbent laminate further comprisesan adhesive between the upper and lower laminate layers.
 7. Theabsorbent core of claim 6, wherein the adhesive basis weight is lessthan about 10% of the SAP basis weight.
 8. The absorbent core of claim1, wherein less than 10% of the weight of the SAP particles reside inparticles that are greater than 500 μm.
 9. The absorbent core of claim1, wherein each layer of laminate comprises a single layer of SAP. 10.The absorbent core of claim 1, wherein the SAP content of each layer ofthe longitudinally folded multi-layer absorbent laminate is from about40 gsm to about 150 gsm and wherein total SAP content of the layers ofthe longitudinally folded multi-layer absorbent laminate is from about7.4 g. to about 18 g and the total SAP content of the layers of thelongitudinally folded multi-layer absorbent laminate is between about240 gsm to about 600 gsm.
 11. A disposable absorbent article comprising:a body-facing topsheet; a backsheet; and an absorbent core of claim 1disposed between the body-facing topsheet and the backsheet with thechannel facing the body-facing topsheet.
 12. The disposable absorbentarticle of claim 11, further comprising a through-air bonded (TAB)acquisition distribution layer (ADL) positioned between the topsheet andthe absorbent core, wherein the ADL width is at least 80% of folded corewidth.
 13. The disposable absorbent article of claim 11, furthercomprising a cellulosic acquisition fiber between the topsheet and atleast a portion of the absorbent core of claim
 1. 14. The disposableabsorbent article of claim 11, wherein the core and the absorbentarticle are stable and the absorbent article has a stability rating ofat least 35 drops.
 15. The disposable absorbent article of claim 11,further comprising a surge core disposed between the body-facingtopsheet and the absorbent core of claim
 1. 16. The disposable absorbentarticle of claim 15, wherein the surge core comprises a longitudinallyfolded, multi-layer absorbent laminate defining a longitudinal channel,and the surge core is centered over the channel of the absorbent core ofclaim 1.